One of the blogs I read regularly is the Techno Constructivist by Carl Anderson. An awesome site of resources that are really focused on use in the classroom. Last week he put out a revised version of his digital backpack.
Carl's digital backpack is a range of web 2.0 sites that he uses. He revised his backpack to comply with new regulations (COPPA) regarding students use of web 2.0 sites particularly the age appropriateness and privacy concerns of sign ups.
Plenty there that I haven't heard of.
Makes me think that I should put together a opensource / free software backpack.