So I just found this cool program called Mixed-In-Key. It will analyze all your music and tell you what key its in so you can mix you mixes better by selecting songs that are of the same key. Its pretty cool. It works on the principle of “Harmonic Mixing.”

From their website:

Bottom line, harmonic mixing eliminates key clashes. When you mix harmonically, your vocals, melodies and basslines will all be in key (harmony). Harmonic mixing helps you achieve a ‘live mash-up’ effect and encourages creativity. You’ll discover unusual song mixing combinations, like The Beatles vs. Jay-Z, or you can simply enjoy flawless DJ mixing, like Armin Van Buuren, Paul Van Dyk and Sasha.

With harmonic mixing, it’s essential to know the key of every song you play. Mixed In Key software scans your entire music collection (MP3s and WAVs) to make this easy. When scanning is done, Mixed In Key displays your results in the Camelot Easymix notation (e.g. 4A, 6B) or Flat/Sharp notation (e.g. F minor, B-flat minor).

Mixed In Key is easy to use. Simply add your music to the Analyze Songs window, click Start Processing and Mixed In Key will show you which songs mix together without a key clash. Using the results will give you a harmonic mix every time.

Our software works perfectly with all CD decks, Ableton Live, Traktor, Torq, and all other mixing software and hardware. You can use your current DJ equipment with Mixed In Key.

Ive got a Powerbook G4 with 1gb or RAM and it took about 5 hours to analyze 560 mp3 files. Mixed-In-Key is available for both Mac OS X 10.4+ and Windows 2000, XP and Vista (if your unfortunate enough to own a Windows PC).

Its not free, it cost $58, but its worth it. Check out their website (click the link above) and watch the demo, youll be sold in a minute once you see it in action. However, it did take quite a while to analyze my files. But another cool thing that it does is that it will write the key information to the ID3 tag of the file so you wont forget your songs key. And it also lets you choose how and where it writes the key information.