Top 5 (in no particular order and excluding the CR):
Google Reader — I practically live here. I’m subscribed to a *lot* of RSS feeds (more than I actually have time to read), and Google Reader does an excellent job of organizing it all for me.
Facebook — I keep in touch with friends and family quite extensively through FB.
Wikipedia — Yeah, I read a lot of that as well. Usually pretty good for when I need a quick fact or some basic background information on a subject.
Google Docs — I use Google Docs quite extensively.
(My mail provider) — obvious
The Wolf