UltraMixer, a nice DJ application runs on Windows, OS X and Linux, too. It has three levels: the very simple Free is rather a sample, and works for two hours at a time. Basic for 109 USD has no such disadvantage, and Professional has numerous goodies for 239 USD. The lattest has ASIO support, real-time effects, time-stretch, sample player, looper, 31-band graphic equaliser, BMP-counter, controller interface and so on. Check here if you are interested more.