I had previously worked with Diigo (very briefly) and had been quite pleased with it but on revisitation I didn't really get it. So, I decided to have a look at Delicious. I liked the fact that it used a mac in the instructions section...very helpful for a new mac user! I took to it pretty quickly and have saved all my bookmarks with tags etc. and can see that being quite useful when I come to working in the library at uni and might be on another machine. I can't really see myself using the networks etc. but it is certainly a very useful tool for personal use.
I haven't had a go with the 'ReaditLater' thing since the new Lion software for macs has a similar function as a button on the Safari toolbar and the symbol looks like this:
|Very cool shelf stairs|
It does look good that you can browse by shelf since this is something that students said they missed when dealing with ebooks etc. I don't really see how helpful the rating system is when Library Thing is in an academic role. I know that LibrarySearch has a link to Library Thing and shows how many people own the book (on Library Thing) and how they rate it - this would not have affected the likelihood of me reading a book on my reading list. This is coupled with 'My discoveries' and I don't know how widely they are used by Cambridge University students. Perhaps it is more useful for research and wider reading i.e. when you go off the reading list. I certainly never felt the urge to rate the books on my reading list on the actual catalogue. Maybe that is just the sort of student I was!