I have a Google Docs account. So far, I've used it to edit a shared multimedia presentation. I thought about using it for the library handbook, but felt the handbook was to personal for our district. I thought about shared editing of the curriculum scope and sequence, but again too much personal information.
If I was going to continue in the Middle School next year, I would explore using this with my students.
I have looked at Library Thing and Good Reads. I like the concept and love the fancy book covers on the shelf concept. I have to be honest and say that I don't want to catalog my books at home. (I like them messy and unorganized.) I'm also not fond of the fact that the sites link to book sellers. I don't feel that we should be encouraging one vendor over another - just to get glitzy images.