library thing - http://www.librarything.com
LibraryThing is an online service to help people catalog their books easily. Because everyone catalogs together, you can also use LibraryThing to find people with similar libraries, get suggestions from people with your tastes and so forth. - [Read more]

unalog - http://unalog.com
You can look at what various people and groups of people are reading on the web here. You can get an account and add your own links, and create and join groups here too. If you get an account, or create a group, either one can be made private, so nobody b - [Read more]

MetaWishlist.com - http://www.metawishlist.com/
MetaWishlist.com is a community built around the things you want. This is a place to gather your wish list items from anywhere on the net and keep them all in one, convenient place. - [Read more]

MyProgs - http://myprogs.net/
This site allows you to keep a social list of the programs you use. - [Read more]