I'll give it a whirl.

1) Killed Osama bin Laden
2) Pased credit reform (not all he wanted but I know MY bills are easier to read)
3) Kept us out of a Depression with TARP (mostly inherited from Bush and poorly written to allow the banks to get away with more crap but it was better than the alternative)
4) Eliminated DATD (I know it's a matter of opinion for many, but it seems to be going over well where I work)
5) Got the Consumer Protection Bureau started (again, not as good as it should be but it's a start)
6) Produced a timetable for getting out of Iraq. (Now if we could only do the same for Afghanistan, South Korea, Germany, Italy and the other 100+ countries were in)