Most popular software is PCDJ Red, PCDJ Fx and Mixmeister, although IMHO nothing is so good like Winamp 2.91/2, MEXP plugin, advanced crossfader and the AdaptX for your off-the-console audio effects. last two are free for Winamp 2.X, MEXP is commercial but more than ten times cheaper than Mixmeister and PCDJ- AND better.