brotherhood_of_LAN - 9:33 pm on Jul 17, 2011 (gmt 0)

Essentially you're looking for expired domains, anything with a year in it will more likely have expired (in most general terms), e.g. the london olympics 2012 will have a number of domains hyping up the event for next year but by 2015 I imagine a lot of them will be up for grabs.

Bankrupt 'free' web hosts would be another one to consider, whether they use subdomains or subfolders.