cue

CUE is the most reliable, intuitive DJ software. It empowers DJs to mix, scratch, juggle, and sample audio and video on its dual virtual decks.

Just load tracks from your virtual crates to the virtual decks and mix it up.
CUE enables you to play directly from a CD or from a variety of digital audio files including MP3, MP3Pro, MP4, M4A, WAV, AIFF, DVD, WMV, CDA, WMA, ASF, OGG, and iTunes ACC (non-DRM).