I still get a _little_ annoyed at myself for not keeping at least some of the ~60BTC I mined in April-June 2011 (early enough that I have Mt. Gox support emails answered by Mark Karpeles). I basically come to the conclusion that it was going to be a flash in the pan, so offloaded them as soon as they were mined.

That said, I would definitely have sold them long before their current price, so I don't see it as a great loss.