Dance music is hard to get right. Before our balls my sister and I have a lot of work to do. The music needs to be the right speed for each dance, provide a solid beat, give the right mood, and let the dancers get through the dance several times. Here's a few useful doo-dads.
I usually splice and loop the songs using GoldWave Editor. Sometimes I get carried away and make them too long, and sometimes I go crazy listening to the same phrase over and over again, trying to cut it in the right spot.
Beats-per-minute counter This thing could be real useful if you want to tack metronome beats on to the beginning of a song (if it doesn't have an introduction) or just to give you an idea of speed.
A definite recommendation of this CD. The songs are at nice dancing speeds and the beat is always laid down nicely. Some of the songs are a bit short, but that's what I use GoldWave for.