Indiana and Kentucky start coming in at 6PM EST. Look for the county-by-county returns in Baron Hill's House district (IN-9) in Southern Indiana-Obama won't win there, but if he is keeping it pretty close he's in VERY good shape for the rest of the state, and likely the rest of the election overall. Also watch the Souder House District in NE Indiana, this is a very red seat that is shockingly close. If it does start to trend towards the challenger Montagano, it could mean that the upper range of the Dem tide could be coming in.
Also, of course, there is Kentucky Senate race-watch Jefferson and Fayette counties-specifically if the margins get higher than 60/40 or so in them it's going to be a bit before they can call it for McConnell, which doesn't bode well in general for the GOP.