| Name  | Description/Focus | Registered Users | Registration |
| 43 Things | Goal and Dreams; Tagging | &&&&&&&&01007433.&&&&&01,007,433 | Open |
| Advogato | Free and open source software developers | &&&&&&&&&&011000.&&&&&011,000 | Open |
| Amina - Chechen Republic Online | Chechens | &&&&&&&&&&&03500.&&&&&03,500 | Open |
| ANobii | Books | &&&&&&&&&&&&&&-1.1000000 Unknown | Open |
| aSmallWorld | European jet set and social elite | &&&&&&&&&0150000.&&&&&0150,000 | Invite-only |
| Badoo | European young adults | &&&&&&&012000000.&&&&&012,000,000 | Open |
| Bebo | General, Popular in UK, Ireland, New Zealand | &&&&&&&040000000.&&&&&040,000,000 | Open |
| BlackPlanet | African-Americans | &&&&&&&016000000.&&&&&016,000,000 | Open |
| Blue Dot | Link sharing | &&&&&&&&&&080000.&&&&&080,000 | Open |
| Broadcaster.com | Video sharing and webcam chat | &&&&&&&026000000.&&&&&026,000,000 | Open |
| Buzznet | Music and pop-culture | &&&&&&&&&0550000.&&&&&0550,000 | Open |
| Capazoo | General (blogs, photos, music, videos) | &&&&&&&&&&&&&&-1.1000000
| Open |
| CarDomain | Car enthusiasts | &&&&&&&&01600000.&&&&&01,600,000 | Open |
| Care2 | Green living and social activism | &&&&&&&&07744297.&&&&&07,744,297 | Open |
| Classmates.com | School, college, work and the military | &&&&&&&040000000.&&&&&040,000,000 | Open |
| Consumating | "Consumeetings" | &&&&&&&&&&021000.&&&&&021,000 | Open |
| CouchSurfing | Hospitality | &&&&&&&&&0281000.&&&&&0281,000 | Open |
| Cyworld | Young South Koreans | &&&&&&&021200000.&&&&&021,200,000 | Open |
| Dandelife | Collective narratives or "shared biographies" | &&&&&&&&&&&&&&-1.1000000
| Open |
| Del.icio.us | Link sharing. Owned by Yahoo!. | &&&&&&&&&&&&&&-1.1000000 Unknown | Open |
| Dodgeball | Mobile location-based service. Owned by Google. | &&&&&&&&&&&&&&-1.1000000
| Open |
| DontStayIn | Clubbing (primarily UK) | &&&&&&&&&0333000.&&&&&0333,000 | Open |
| Doostang | Careers | &&&&&&&&&0173000.&&&&&0173,000 | Invite-only |
| eCRUSH | Teens | &&&&&&&&04400000.&&&&&04,400,000 | Open |
| Experience Project | Life experiences | &&&&&&&&&&&&&&-1.1000000
| Open |
| Facebook | General. Popular in Canada, UK and USA. | &&&&&&&073500000.&&&&&073,500,000 | Open |
| Faceparty | British teens and young adults | &&&&&&&&05900000.&&&&&05,900,000 | Open to people 16 and older. |
| Flickr | Photo sharing | &&&&&&&&04000000.&&&&&04,000,000 | Open (Yahoo! login) |
| Flirtomatic | Flirting/Dating | &&&&&&&&&0265000.&&&&&0265,000 | Open to people 18 and older. |
| Flixter | Movies | &&&&&&&036000000.&&&&&036,000,000 | Open |
| Fotki | Photo sharing | &&&&&&&&01000000.&&&&&01,000,000 | Open |
| Fotolog | Photoblogging | &&&&&&&012695007.&&&&&012,695,007 | Open |
| Friends Reunited | School, college, work, sport and streets | &&&&&&&019000000.&&&&&019,000,000 | Open |
| Friendster | General | &&&&&&&026500000.&&&&&026,500,000 | Open |
| Frühstückstreff | General | &&&&&&&&&&011600.&&&&&011,600 | Open |
| Gaia Online | Anime and games | &&&&&&&&09300000.&&&&&09,300,000 | Open |
| Gather | Article, picture, and video sharing, as well as group discussions | &&&&&&&&&0360000.&&&&&0360,000 | Open |
| Geni.com | Families, genealogy | &&&&&&&&&0750000.&&&&&0750,000 | Open |
| Grono.net | Poland | &&&&&&&&01350000.&&&&&01,350,000 | Invite-only |
| GuildCafe | Online games | &&&&&&&&&&&&&&-1.1000000
| Open |
| hi5 | General | &&&&&&&050000000.&&&&&050,000,000 | Open |
| Hospitality Club | Hospitality | &&&&&&&&&0328629.&&&&&0328,629 | Open |
| Hyves | Dutch | &&&&&&&&03266581.&&&&&03,266,581 | Open |
| imeem | Music, Video, Photos, Blogs | &&&&&&&016000000.&&&&&016,000,000 | Open |
| IRC-Galleria | Finland | &&&&&&&&&0400000.&&&&&0400,000 | Open |
| iWiW | Hungary | &&&&&&&&02600000.&&&&&02,600,000 | Invite-only |
| Jaiku | General. Owned by Google. | &&&&&&&&&&&&&&-1.1000000
| Open |
| Joga Bonito | Football (soccer) | &&&&&&&&&&&&&&-1.1000000
| Open |
| Last.fm | Music | &&&&&&&015000000.&&&&&015,000,000 | Open |
| LibraryThing | Book lovers | &&&&&&&&&0214425.&&&&&0214,425 | Open |
| LinkedIn | Business | &&&&&&&016000000.&&&&&016,000,000 | Open |
| LiveJournal | Blogging | &&&&&&&012900000.&&&&&012,900,000 | Open (OpenID) |
| LunarStorm | Sweden | &&&&&&&&01200000.&&&&&01,200,000 | Open |
| MEETin | General | &&&&&&&&&&072000.&&&&&072,000 | Open |
| Meetup.com | General | &&&&&&&&02000000.&&&&&02,000,000 | Open |
| MindViz | Custom Profiles, Photo & Video Sharing, Music, etc... | &&&&&&&&&0145000.&&&&&0145,000 | Open |
| MiGente.com | Latinos | &&&&&&&&03600000.&&&&&03,600,000 | Open |
| Mixi | Japan | &&&&&&&&09830000.&&&&&09,830,000 | Invite-only |
| MOG | Music | &&&&&&&&&&&&&&-1.1000000
| Open |
| Multiply | "Real world" relationships | &&&&&&&&05000000.&&&&&05,000,000 | Open |
| MyChurch | Christian Churches | &&&&&&&&&&070306.&&&&&070,306 | Open |
| My Opera Community | General (blogs, photo albums, forums, groups, etc.) | &&&&&&&&01001798.&&&&&01,001,798 | Open |
| MySpace | General. Popular in the USA. | &&&&&&0289000000.&&&&&0289,000,000 | Open |
| myYearbook | General | &&&&&&&&&0950000.&&&&&0950,000 | Open |
| Netlog | Formerly known as Facebox. | &&&&&&&028000000.&&&&&028,000,000 | Open |
| Nexopia | Canada | &&&&&&&&01158531.&&&&&01,158,531 | Open |
| OkCupid | Dating | &&&&&&&&&&&&&&-1.1000000
| Open to people 18 and older |
| orkut | Owned by Google. Popular in Brazil and India. | &&&&&&&067000000.&&&&&067,000,000 | Open (Google login) |
| OUTeverywhere | Gay | &&&&&&&&&&&&&&-1.1000000
| Open |
| Passado | General | &&&&&&&&04700000.&&&&&04,700,000 | Open |
| Piczo | Teenagers, Canadians, photo sharing | &&&&&&&010000000.&&&&&010,000,000 | Open |
| Playahead | Swedish teenagers | &&&&&&&&&0530000.&&&&&0530,000 | Open |
| Playtxt | Mobile social network, location, worldwide | &&&&&&&&&&070000.&&&&&070,000 | Open |
| Pownce | Websites, files, and short updates | &&&&&&&&&&&&&&-1.1000000
| Invite-only |
| ProfileHeaven | British teens | &&&&&&&&&0100000.&&&&&0100,000 | Open |
| RateItAll | General (consumer ratings) | &&&&&&&&&&&&&&-1.1000000
| Open |
| Reunion.com | Locating friends and family, keeping in touch | &&&&&&&028000000.&&&&&028,000,000 | Open |
| Ryze | Business | &&&&&&&&&0250000.&&&&&0250,000 | Open |
| Searchles | Social search and networking | &&&&&&&&&&&&&&-1.1000000
| Open |
| Sconex | American high schools | &&&&&&&&&0500000.&&&&&0500,000 | Open |
| Sermo | Physicians | &&&&&&&&&&020000.&&&&&020,000 | Open only to registered D.O.s and M.D.s in the U.S.A. |
| sexi | Japan (sexual networking site) | &&&&&&&&&&060000.&&&&&060,000 | Invite-only |
| Shelfari | Books | &&&&&&&&&&&&&&-1.1000000
| Open |
| Skyrock Blog | France, Belgium, French Polynesia, Guadeloupe, Martinique, New Caledonia, Senegal | &&&&&&&&03800000.&&&&&03,800,000 | Open |
| Snooth | Wine | &&&&&&&&&&&&&&-1.1000000
| Open |
| Soundpedia | Music | &&&&&&&&03500000.&&&&&03,500,000 | Open |
| Sportsvite | Recreational sports | &&&&&&&&&&018000.&&&&&018,000 | Open |
| StudiVZ | University students, mostly in the German-speaking countries | &&&&&&&&02400000.&&&&&02,400,000 | Open |
| Tagged.com | General | &&&&&&&030000000.&&&&&030,000,000 | Open |
| TagWorld | General (tagging) | &&&&&&&&01850692.&&&&&01,850,692 | Open |
| TakingITGlobal | Social action | &&&&&&&&&0145000.&&&&&0145,000 | Open |
| The Student Center | Teens and colleges | &&&&&&&&&0800000.&&&&&0800,000 | Open |
| Threadless | Custom T-shirts | &&&&&&&&&0364474.&&&&&0364,474 | Open |
| TravBuddy.com | Travel | &&&&&&&&&0760000.&&&&&0760,000 | Open |
| Travellerspoint | Travel | &&&&&&&&&0105000.&&&&&0105,000 | Open |
| tribe.net | General | &&&&&&&&&0602876.&&&&&0602,876 | Open |
| TuneDNA | Music | | Open |
| Twitter | General | &&&&&&&&&&&&&&-1.1000000
| Open |
| Vox | Blogging | &&&&&&&&&&&&&&-1.1000000
| Open |
| WAYN | Travel and lifestyle | &&&&&&&&08000000.&&&&&08,000,000 | Open to people 18 and older |
| WebBiographies | Genealogy and biography | &&&&&&&&&&&&&&-1.1000000
| Open |
| WeeWorld | General (cartoons) | &&&&&&&&01700000.&&&&&01,700,000 | open |
| Windows Live Spaces | Blogging (formerly MSN Spaces) | &&&&&&&040000000.&&&&&040,000,000 | Open |
| Woophy | travel & photography, photo sharing website | &&&&&&&&&&023000.&&&&&023,000 | Open |
| Xanga | Blogs and "metro" areas | &&&&&&&040000000.&&&&&040,000,000 | Open |
| XING | Business | &&&&&&&&04000000.&&&&&04,000,000 | Open |
| Yahoo! 360° | Linked to Yahoo! IDs | &&&&&&&&04700000.&&&&&04,700,000 | Open to people 18 and older, (Yahoo! login) |
| Yahoo! Mash | Yahoo's new SNS - Still in beta | &&&&&&&&&&&&&&-1.1000000
| Invite-only while in beta |
| Zooomr | Universal photo sharing | &&&&&&&&&&&&&&-1.1000000
| Open (OpenID) |
