I recently had a member PM me asking about my cover crop. I thought it was a good question that I can't remember if I covered or not so I thought I would post it up in case anybody else was wondering.
I use a blend of many, many clover types...
http://www.groworganic.com/low-growing-clover-mix-rhizocoated-lb.html
http://www.groworganic.com/subterranean-clover-mix-rhizocoated-lb.html
http://www.groworganic.com/dryland-clover-mx-rhizocoated-lb.html