Well, there's not a whole lot he can actually do (at least not permanently), he can't push any far left legislation through congress because the house remains Republican. If he releases any crazy executive orders, they can be rescinded by Romney on day 1, ditto with any departmental regs. I think the worst thing he could do is issue mass pardons or something.
He can release a lot of thugs from prison, alright.
That would do a lot of damage.