Here is another list of the "top 10 websites you should know about." This list includes Writely which I have been using more and more for my word processor; I wrote about it last month.
It also includes an interesting site that I had not seen before: Meebo. For a number of years, I have used Trillian as a single client to log on to multiple IM services, including ICQ, Yahoo, Jabber, MSN and AOL. Meebo is a web based client that provides the same basic functionality without having to install a thick client.