The main thing we need to do is get back to real, darwinian consequences for stupid behavior. Banks would NOT have made all those "toxic" loans, nor would they have been able to bundle them into derivative products (because nobody would have bought them), if they had been exposed to the real risks they were taking on.
If you make clear rules and get people to follow them, and people see that everyone else is following the rules, that makes following the rules normal and rule-breaking an unusual transgression, even without a panopticon.
It's tricky to pull off, but how else would you do it?