Google is not blocked normally (both the China/HK version and the US version), though Google Sites and parts of Google Docs are. Censoring sometimes kicks in, though, if you do too many image searches (the pictures stop loading). I imagine search results for sensitive topics might be censored, too.

Blogspot and Wordpress are usually blocked, but occasionally you can get through.

Flickr also does not appear to be blocked at the moment (just tested it now).

YouTube and Facebook are always blocked!