Here's a great video and Ableton session which includes a library of chords that are all separated by key. The session and all the clips are colour coded to the circle of fifths diagram Subaqueous has mofified, making it very easy for you to program chords into your music whilst staying in key. If you are like me and aren't very familiar with the music theory side of things then this will seriously help your song writing.
If you aren't using Ableton, the download also includes the MIDI files of the chords in each key. Thank you Subaqueos!
The session download is all available from Subaqueus ,where you can also find other tutorials, instruments and sessions for you to download. The site is full of useful freebies and you can make a donation to his site if you like.