I buy expired B&W when I see it really cheap. I don't use it for anything critical though, and always expect the worst. I have a few rolls of Verichrome Pan from the late 1960's that I found in a $1 box at a camera show. I've only shot one roll so far but it came out really well:

http://www.flickr.com/photos/rjbuzzclick/4040653692/

http://www.flickr.com/photos/rjbuzzclick/4038189890/

I shot it at 64 ASA and developed it in Daifine.