Newly updated list of top social networking sites.

Facebook
Facebook is a social network where you can connect with people at specific schools or companies, in specific regions, etc. Members must be affiliated with a particular group or groups (users can belong to up to five different groups) to participate. Members must be at least 13 years old. Member information can be shared only with other members of the same group.
http://www.facebook.com

MySpace
MySpace is a free social network where members create their own web pages. Typical pages include a biography, pictures, an online journal and more. Members can also share videos and music, look at job listings, scan classified ads, join chat rooms, play games, watch music videos, form a social network, and invite friends to visit their MySpace page. The site is open to everyone (individuals, families, groups, companies, organizations, etc.) ages 14 and older. Before joining MySpace, read the safety tips provided.
http://www.myspace.com

43 Things
43 Things is a social network where members can list up to 43 goals they would like to achieve (climb a mountain, swim the English Channel, bike across the USA). Members can list original goals or read the goals of other members and decide to use someone else's goal. Members share their experiences and knowledge and help one another achieve the goals on their lists.
http://www.43things.com

Bebo
Bebo is a social network available in the USA, Canada, UK, Ireland, Australia and New Zealand. Members can keep in touch with college friends, contact friends, discover new interests, share photos, keep blogs, view videos, and listen to music. Members can also elect to keep their home page private and limit access to only their friends. The bands page lists new music available only on the site, and then shows additional music available by category (such as Pop, Rap, Hip Hop, etc.), the TV page lists videos (some sponsored) available for viewing (including music, sports, news, art, etc.).
http://www.bebo.com

Sconex
Sconex is a social network for high schools. Members can locate their school, enter their profile, share photos, learn about their classmates, post a blog, post and read messages from their school, clubs, and classes, see what's popular at their school, and take fun quizzes.
http://www.sconex.com

Classmates
Classmates.com is a social network where you can find and reconnect with high school, college and military friends. Look up your school and find out about reunions and other social events. There is a free membership that allows users to post photos, see who is missing from your graduation class, build a profile, locate friends, create announcements, and post messages. Their fee-based membership includes email services, access to the bios of other members, see who visited your bio, reply to notes, and plan reunions and events.
http://www.classmates.com

Friendster
Friendster is a social network where members can keep in touch with friends, maintain a blog, and meet new people who share the same interests. You can also view videos, see a listing of classified ads by country that list events, people, resumes, jobs, items for sale, reviews, housing and business services. Members have options to keep their profiles private, make them available to specific people, and available to all members.
http://www.friendster.com

Orkut
Orkut is a social network (and Google affiliate) that allows members to share pictures and messages. Members can join through their existing Google account or can get a new Google account. Members can locate other memebers who share the same interests.
http://www.orkut.com

IMBEE
IMBEE is a safe social network for children ages 8 to 14. The site is free but to ensure that there is parental approval they require that a parent supply a credit card account. Members can create blogs, create an avatar, send and receive messages and share photos.
http://www.imbee.com

Hi5
Hi5 is a social network where members can meet other members world wide. Members can keep in touch with friends, meet new people, create content and explore other content posted to the site, send and receive messages, post, view and rate videos and pictures, upload and download music, join a group or create a group, and locate other members from their school or college (listed by state).
http://www.hi5.com

MyYearbook
MyYearbook is a social networking site founded by teenage siblings (a high school junior and senior) and their older, Harvard-educated (and investor) brother. Members create a profile, then add their school classes (math, English, etc.) and list the students in the classes, create a locker (to hold photos, MP3s, movies), vote for "Bests" (athlete, student), give out gold stars, view other members' yearbooks, comment on pictures (yours and other members'), leave an autograph, form groups and clubs, create a top-10 list, post forums, maintain a personal calendar, take polls, leave a will (memories that you leave to friends), and post a blog.
http://www.myyearbook.com

Zigime
Zigime.com is a newcomer to the social networking arena. Picking up where most of the present social networking sites have left off, Zigime.com has many unique features and one that's especially cool - the Friend Manager feature will be a welcome relief for the many members who love to collect hundreds of thousands of friends and then be able to search and sort by age, gender and location.
http://www.zigime.com