Heh... I haven't found anything really cool for DJing under open-source platforms... That's why I'm stuck with a Windows laptop with iTunes (DRM tracks) and a few Windows applications to calculate the BPM and the Key of the tracks...
Then I burn CDs and go play with my CDJ-1000mk3 s
What kind of mixing are you doing? Do you plan to go pro?
BTW: let me know if you find anything cool for open-source platforms.