While looking for a reading list for a student who might be doing some work on social software I came across this interesting-looking site, H2O Playlists:
An H20 playlist is a shared list of readings and other content about a topic of intellectual interest. It is a simple yet powerful way to group and exchange useful links to information – online and offline.
For the list I found on social software, for instance, you can continue on to lists that influenced that list, to lists that were based on that list and to lists that contain some of the same items as that list.
Potentially an interesting counterpart to CiteULike.org, where you bookmark and tag individual academic articles and books rather than whole lists. Looks as though it would be easy to create and manipulate lists.