Diigo
Okay, Diigo is really cool. Especially in a job like mine where I do a lot of research. Diigo is a social annotation site so if you like surfing the net and want to leave notes on your favourite websites, Diigo is the program to do it. Registration is free and there is no download required for basic Diigo. It allows you to leave virtual "sticky notes" on the websites you visit. The really cool part? You can share your "online" notes with people of your choosing.