Thanks to Richard Byrne for his post on Free Technology For Teachers. (Highly recommended).
LiveBinders seems excellent – I tried it and created a binder including some favourite websites on equations and a screenr recording of how to use one of the sites.
Update – LiveBinders is still excellent! It is extremely easy to use and I like the presentation.
I used it to create a binder on Wordle which is something everybody seems to be talking about!