During the summer of break of 2006/7 I spent some time working on the famous Two-Envelope Paradox. I embarked on this project after reading the WIKIPEDIA entry on this topic.
In my humble opinion the version currently (4:37AM, January 20, 2007 ) available there is terribly wrong.
So you might be interested in reading my article The Two-Envelopes Paradox: A Primer for Dummies on this topic. There are some interesting results there.
