Fan.

This is the cheap-o fan that sits on my bedside table. It gets me through the warm nights. I also try to use it in cooler nights as well. Basically any nights I can get away with. You see it's not just the cooling it provides on those warm nights, but I like the sound just as much. I like to have some sort of soothing repetitive sound to drift off to sleep with. A completely silent room is a terrible environment for me to fall asleep!