This one came Ken Rockwell recommended. Expensive, but works well with my Canon EOS 1Ds Mark II. A far site better than my FD to EOS POS adapter.
It is easy to attach but a little diffcult to remove. I didn't receive instruction with it, but figured out after a little trial and error that it can be simply removed by depressing the small lever on the side, (and I do mean small).
The other reviews I read recommended having a seperate adapter for each lens but at that price I can live with my one, though I am looking for another at a cheaper price. Two would be twice as nice.