Which web 2.0 services do scientists use?

Very interesting informal study:

Which web 2.0 services do scientists use?

Almost a third of Friendfeed scientists have delicious bookmarks. Don't discount non-academic bookmarking services as a source of paper metadata.
A similar number use the share functionality in Google Reader.

Despite rumors to the contrary not everybody is on Twitter.

A surprising (to me) number of people are uploading and favouriting items on Slideshare.