I find that RememberTheMilk is great for keeping track of what I should be doing but I also like to keep track of what I'm actually doing -- where the time actually goes. Right now, I'm using pen & paper which is starting to feel a bit quaint to me. (Querying seems to involve more paper cuts that suits me.) I'd like to find a web app which can keep this data for me -- bonus points if it syncs to desktop/phone/etc.
Edit: I'm not really looking for a time tracker -- just somewhere that I can enter what I'm working on. A time-tracker seems like (a) overkill and (b) something that might keep track of what I'm doing on my PC but not "meeting with KK & JK re: Project Boofus."