I've notices that the various coffee-based developers (specifically "Caffenol LC+C" - [Kudos to Donald Qualls for that one], seem to work very well, especially considering that they're made from coffee and washing soda.

So, I've been wondering: what is it in the developer that acutally causes it to work? I know that coffee contains, tannins, phenols, a host of acids, and lots of other chemical goodies.

Can anyone give any chemical insight into this?