Allegations of selling cocaine when in in college.
The first two are pretty lame: people are tired of birther conspiracies and whatever the rift, the Obama marriage seems to be on solid ground now. The third allegation may be serious enough to warrant attention, but extremely difficult to prove, since Obama would have covered up all evidence of any drug deals long ago. It's about as baseless as the "Obama had a gay lover" attack.
Of course, the Donald has said that his revelation will "change the course of the election," meaning he could just as easily have something on Romney (Trump is always hungry for publicity either way)
With 12 full days to go until the election, at the rate about two "October surprises" per day, that leaves us with almost 24 more to go.
Can we stand it?