I am still kicking myself to this day I didn't throw money into AIG when it was trading around $1-2 per share. I did make out decently off BoA stock in the same time period though.
I bought a little at the low (but didn't have much money to play with at the time, so we're talking extremely small potatoes all around) but also put quite a bit (relatively) into Freddie, reckoning they'd also pop back plenty fast with government intervention.
Whoops.