(There's no video for Native Instruments Traktor 2.5 yet. Please contribute to MR and add a video now!)
This is a key piece of software that helped legitemize digital and computer based DJing and helped launch Native Instruments into the success it is today.
It is still highly functional for professional grade digital DJing with support for MIDI control surfaces, plugins, MIDI master clock syncing, beat grids, custom hotkey maps and much, much more.
traktor_cd1.iso (335.95 MiB / 352.26 MB)
Mac OS 9 / ISO image
Emulating this? It should run fine under: QEMU