Thinking about sites for students

I looked at three sites: Backpack, Digication, and Notecentric. Of the three Backpack struck me as the most useful. Perhaps because it had the best "tour". Backpack strikes me as a very flexible and user-friendly organizational tool. Notecentric also appears to have a lot of potential for sharing information among students. It is a Facebook application, but that shouldn't be a limiting factor, since Facebook is free and practically every student I know already has an account anyway. Digication was a bit more confusing. There was no tour of the site, and no obvious explanation of it's usefulness. How do people find out about these sites and know what to do with them? It's a mystery to me. I'm glad the krl2pt0 site will be staying up--I'm sure I'll come back to it in the future to find some of these sites, or just for a refresher.