Watch the Use a Partial Capo online guitar lesson by Vicki Genfan from Acoustic Rhythm Survival Guide
The capo I'm using in the video is a 'short cut' Kyser capo with the 'lever', which lets you press down the 6th string easily if you want to.
Here's a site that will go into all the detail you want about these fun inventions: Partial Capo.net
Randall Williams will show you more than you probably want to see about partial capos! In the meantime, this is wide-open territory. You have to explore. Try playing all the chords you already know in standard tuning with the partial-capo on.
Start with the capo on the second fret. Then try moving it up and down the fret board. Listen to what happens! Keep your recording device ON!
There are many companies making partial capos, and I like them all. Shubb, Kyser, Planet Waves are a few that I think are high quality. I think G7 capos will have a version soon too.