A popular activity on the Internet has always been connecting with other people, so Social Networking sites have become very popular.
A variation on social networks, the Blogosphere offers you way to participate in reading and writing diary-like entries about a range of topics.
You can use Google Groups to search and read the massive online community formerly known as Usenet which was used extensively by the ancient Geeks.
If you are trying to find people, check out the Top People locating resources of the Web.
See also: Internet Tools Summary---Communication