Green up your shedworking lifestyle with some eco-friendly flooring. There's a useful list of suggestions at Treehugger which suggests:
* Reclaimed wood
* Cork tiles
* Mud (yes, mud)
If you haven't come across the New York-based Treehugger, it's well worth a browse around. They describe themselves as "dedicated to everything that has a modern aesthetic yet is environmentally responsible" which is a pretty wide remit and they do cover a lot of ground, usually very internationally.