I added a vertical ad strip to the individual post archives three months back.
1$ per day
peeks made less money
AdSense sucks for some technical posts: HTTP request scheduling -> meeting scheduling software... Can we provide non-paying but actually relevant links instead?
http://www.intertwingly.net/blog/2005/03/31/AdSense
1$ per day on browsers that don't support XHTML ;-)
http://www.associateprograms.com/search/adsense.shtml
WordPress fraud
Idea: Shipping website software with AdSense
AdSense hinting
http://www.problogger.net/archives/2005/08/23/adsense-changes-announced/