Mixxx is Free DJ software that gives you everything you need
Midiexplorer is designed to explore a large collection of midi files
audio sequencer
Ballroom Music Player
Simple visual and acoustic metronome with bar-based song part tracking
Your Hardcore Loop Machine for Windows, Linux and OS X.
Loop based software with jack transport, record and midi controllable
Tapita is a BPM detector.
Control Jack transport features using MIDI commands.
Simple musical track editor + Tools