Itsmy
itsmy.com (xhtml-mp/wml)
Registered users can create a mobile home page with profile, blogs and guestbook and can participate in chat, flirting, forums and private messaging. Users also have access to itsmy's online ringtone and wallpaper generators and can upload music, themes videos and images.
The site works more or less like other social networks. You set up your home page and profile and search for and invite others to be friends. User search is by name, age, gender or location. If someone is making you uncomfortable you can block them from interacting with you.
Unique to itsmy is "Its My TV". Using templates, content including text, audio, video and images can be combined into "channels" . There are over 100,000 channels on itsmy with about 100 new shows being produced per day. The videos I saw were all 176x144 and ranged from about 400 KB to 5GB in size depending on quality and length.
Homepage URLs are subdomains (user.itsmy.mobi), which I find easier to type on phones than the sub directories (site.com/user) used by some mobile social networks. Uploading is by MMS from your registered mobile number. Some user generated content like wallpapers is always public but almost everything else including profiles, photos and videos can be set to be viewable only by friends.
Itsmy has 2.5 million total and over a million registered users who have produced 5 million pages of user generated content. The site is averaging 300 million mobile page views per month and operates it's own advertising network. Recent marquee ad clients have included Ford and Reebok but small advertisers are catered to as well.
Itsmy is available in English, German, Italian, Spanish and Japanese. Users are concentrated in the US (over 50% of the total users) followed by South Africa and India.