Using your phone to create or enhance real world interactions is a killer application, but no one has cracked the nut yet. The reason is that the network is useless until it achieves a critical mass of users who are online and using the application via their mobile phone. If no one else is online, there’s little point in you being online, either. And presence detection is another (technical) problem. Even if people have joined the network, how do you know when they are near you?

But once it does happen, look out. You could be in a bar and see who’s single, who thinks you’re cute, who wants to talk to you, etc. (if they choose to share that information). Forget meeting via an online dating site and then organizing an awkward in person meeting that usually falls flat. Instead, you can do the online an real world thing simultaneously.

We’ve kept an eye on the new startups launching in this space. Check out Rummble, Mig33, ZYB, Mocospace, Aka-Aki, Nokia Sensor, Dodgeball, Mobiluck, MeetMoi and Imity, just to get warmed up. But none of them yet have critical mass (Mig33, however, is turning into a very large cheap VOIP provider on the side).

LimeJuice now joins the group with a unique product. Users can actually join on the fly, via SMS. And the company is sponsoring party after party at bars and clubs in San Francisco to get users to try out the product with lots of others at the same time. The test results are encouraging – people are using it. A lot.

How It Works

The goal is to allow people in a bar or other social gathering to learn a little about the people around them, and flirt via the mobile network as a way to break the ice. The details are what makes LimeJuice interesting. It’s dead simple to join and use.

First, users can register for the service via SMS. That means if just one person in a bar is a member or even knows about the service, they can tell others and quickly get a core group to join. When you create an account, you tell it something distinctive about yourself (tall blonde, red dress!) so that people searching will be able to quickly know who you are. When you go to another event later on, you simple update the description for the evening).

Second, all of the key interaction (for now) happens via SMS. So every phone is ready to go. No need to download a java app or even go to a web page. Just send a text message to the service along with the identifier of the person you want to talk to (which you can get via search), and the message is sent to them.

Third, even though people are using the service to send text messages back and forth, phone numbers are not exchanged. LimeJuice sits in the middle, and you can block someone easily.

Beta Events

LimeJuice has seen a good level of participation at the handful of events they’ve sponsored. An average of 40-50 people participate per event. They spend about 1.5 hours each using the service over the course of the evening and average ten text messages sent per person (some people send as many as 180 text messages). At one event, over 2,500 messages were sent to the service from participants.

For now the company will continue to sponsor events in San Francisco, hopefully building up a core user base that will begin to spread out and get others to join. If/when they get a lot of people in San Francisco to use the service, they’ll then expand to other cities.

The company, founded by Tobin Van Pelt and John Garrett, is based in San Francisco and has four employees. They’ve self funded to date with $100,000 and are currently pitching for a Series A round of funding.

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This only works, of course if you A) have friends on Radar, and B) they post pictures on a regular basis. Radar, which launched more than a year ago in the summer of 2006, has only 600,000 users worldwide. But that number has been doubling every month for the past three months. So we might be at an inflection point here, especially as more capable phones come onto the market that can take advantage of its Web-like features. Radar serves 250,000 pictures and videos a day. Eighty percent of its traffic comes from mobile devices (it also has a regular Website), and 70 percent of its users are outside the U.S.

While most of the conversations and photos on Radar are private, you can choose to make them public. And today the company is also launching a public gallery, where advertisers can try to entice Radar members to subscribe to their photo streams. Right now, there are photo streams for the upcoming movie Hitman, pictures of frivolous but funny merchandise from iWoot, top video picks from Vimeo, and CEO John Poisson’s own Radar stream. There will soon be Radar channels from Hendrick’s Gin, iTunes, and the stealth Web video series Nowhere Men (which will focus on a group people “missing” since 2002 and the audience has to help unravel the mystery). This sort of advertising will only work in so far as people don’t see it as advertising, which is why I like it.

Here is a page from Poisson’s Radar channel. Taking picture of food seems to be popular on the site:

And here is what Radar looks like on a regular Sony Ericson phone:

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This is the Holy Grail of mobile social networking, and one of the main reasons for taking the networks off the desktop/laptop environment in the first place. Imagine walking into a meeting, classroom, party, bar, subway station, airplane, etc. and seeing profile information about other people in the area, depending on privacy settings. Picture, name, dating status, resume information, etc. The information that is available would be relevant to the setting – quick LinkedIn type information for a business meeting v. Facebook dating status for a bar.

Knowing when your friends are around, and having the ability to meet new people who share your interests (even if it’s just that you are both single), will drive massive usage of networks. But, as with many new services, a chicken and egg problem looms. Until everyone is using this, there is no real reason for anyone to use it. Meetro, an instant messaging service that finds friends based on location, has struggled to gain users over the last couple of years for this reason.

Technical barriers aren’t an issue – cell phone tower triangulation and bluetooth solve a lot of the problems of locating users and transmitting information between phones. What’s harder is just plain getting a critical mass of users.

The Failures

There is a trail of failed attempts at getting this right. Nokia released Nokia Sensor nearly three years ago. It broadcasts information about yourself to others via bluetooth. Never heard of it? Neither has anyone else, although it is still available for download. Google’s Dodgeball is another example that’s fallen flat – it tells friends (and friends of friends) who are within 10 blocks of you where you are and what you are doing.

The New Experiments

A bunch of new startups are giving this a shot, too. In a post yesterday TechCrunch UK mentions Germany’s Aka-Aki, Paris-based Mobiluck and MeetMoi (the lone U.S. startup). Another startup is Copenhagen-based Imity. It’s not surprising that most of the innovation is occurring in Europe. The current approach is to get java-based software on the phone – very few U.S. carriers and handsets allow user-based installs of java apps.

Aka-Aki

Aka-Aki, based in Germany, is just a couple of weeks old. Create a profile and download the java app to your phone. You can also create and join groups that say things about your life, job, etc. When you are near other people who are members, data about you is transmitted to them via bluetooth, and vice versa. Users have control over data flow with privacy settings. And the groups supply another layer of privacy. You may transmit that you are single only to other singles, for example. Or share your sexual orientation only with others with the same orientation.

After a silent launch, word is getting out. Thousands of people in Berlin are using the software, and there is a chance for them to get critical mass there with proper marketing. The company has raised a small seed round from FoundersLink and is currently looking for a larger round.

Imity

Copenhagen based Imity, which launched in April, has also been flying under the radar. Like Aka-Aki it detects other members via bluetooth and send basic profile information to your phone. It also keeps track of people on its website, so you can check that out periodically from your normal computer. It’s bridges mobile and traditional social networks, which may help it gain critical mass. Co-founder Nikolaj Nyholm is also behind Polar Rose, a facial recognition and image tagging service.

Imity went open source in February 2007.

MeetMoi

MeetMoi, the only U.S. based service, is most like Dodgeball – it uses text messaging to help connect people. It’s dating focused – text your location to the service and it notifies other users in your area that you are there. If they are interested, they can contact you. The company has raised $1.5 million from Acadia Woods Partners and is based in New York.

MobiLuck

MobiLuck, based in Paris, is another bluetooth solution similar to Aka-Aki and Imity. Download the software to your phone and it vibrates when other users are nearby. You can then chat with them, send photos, etc.

Update: Per a comment below, we’re adding Britekite to the list. We actually covered them briefly last month as part of the TechStars event.

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Most of the big networks have mobile versions of their site, with stripped down functionality. Facebook has, hands down, the best mobile application if you happen to own an iPhone. But for the most part, competition in the desktop arena has limited the amount of attention any of the big networks are giving to the mobile world.

That might just give some runway to new startups focused solely on mobile. We recently covered ZYB, a Danish startup that just launched a mobile social network on the back of it’s mobile address book backup service. The specifics of their service largely limit them to Europe, where users have more freedom to add applications to their mobile devices.

In the U.S., one of the stronger contenders is MocoSpace, a Boston based startup that launched a mobile-only social network last year (see coverage at MobileCrunch from April 2006).

The service is very easy to use from a mobile phone. Registration is dead simple – it took about 20 seconds on my iPhone earlier today. Right away MocoSpace starts to suggest possible friends based on proximity, online status or random selections. You can then add photos and video from your phone (or upload them from a desktop/laptop computer), chat with friends, and create a stripped down “blog” which is similar to Twitter in functionality.

MocoSpace says they are serving close to 500 million monthly page views – which is pretty impressive since “almost all” of those page views are from mobile devices. They are also approaching 1 million registered users, and 6,000 new users sign up daily.

MocoSpace raised a $3 million in a Series A financing in January 2007. Investors included General Catalyst, Pilot Group and Michael Deering. The company has 15 employees (half in Boston, half in Israel).

If you are a startup targeting the mobile social networking space, we want to hear from you.

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