For me the biggest mistake I made was probably laziness. I took the fast and easy way of using their calckey instead of taking the extra effort to generate my own keys. Those who generated their own keys weren't affected. Yes I know all about never ever, ever using addresses not generated by your ownself, but I thought it wouldn't hit me. Guess I learned my lesson. So far the lessons I've learned:
Never put btc into exchanges (mt.gox incident)
Never put btc into an online wallet or so called bank (flexcoin incident)
Never mine on a pool (btcguild incident)
Never keep btc in your harddrive (guy who threw out his 7500btc containing harddrive incident)
and now Never use vanity addresses not generated by yourself
So I guess to ONLY way to keep your btc is in a paper wallet kept inside a maximum security vault under constant surveillance. Or am I still missing something?