Mixxx - The most powerful free DJ software in the world.
VirtualDJ - Virtual DJ Software - MP3 and Video mix software for DJs
Zulu DJ Software - Zulu DJ Software is the best tool for singers and musicians.
Traktor Pro - Flagship DJ software with four decks and a stunning range of creative features for maximum freedom in DJing.
VJ6 - If blending music is your essential thought process, you might need to search somewhere else for your DJ blending software.
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.