KeyFinder - Key estimation software for DJs
Mixed in Key - Mixed In Key is award-winning DJ software that gives you the #1 technique of the world's best...
Tunebat - A browser based song key and bpm database. Supplies compatible songs for harmonic mixing.
foo_bpm - A component for calculating the BPMs (beats per minute) of any tracks in Foobar2000.
Audio Beat Detector - A digital DJ oriented automatic Beat Per Minute detecting software
tuneXplorer - Multithreaded BPM and Key detection software for MP3 files.