Mixxx - The most powerful free DJ software in the world.
VJ6 - If blending music is your essential thought process, you might need to search somewhere else for your DJ blending software.
DJ Mixer Soft - DJ Mixer Professional is the best DJ mixing software for Mac and Windows, Support audio, karaoke and video mixing, automatic DJ mixing, one-click beat-matching, etc.
VirtualDJ - Virtual DJ Software - MP3 and Video mix software for DJs
DJ Mix Studio - DJ Mix Studio is full-featured and complete audio mixing software for both professional and novice DJ. DJ Mix Studio's innovative feature set, and user friendly interface will insure that you perform great audio mixes.
Mixmeister - Create custom party mixes, burn CDs, or add special effects to MP3s with this line of DJ software for the novice and pro. Offers free trials and user community.