I've read that with some FD lenses you can actually machine them to work at infinity. I don't know. I haven't done that and wouldn't be motivated to try.

Other than that some vintage stuff is also worth a look. I bought this old Zeiss Flektogon 20mm prime, very nice "zeissish" look.

Yes indeed, I second that -- my favorite lens (especially when it comes to DOF & bouquet) is an old classic f/1.4 Carl Zeiss that I got from some underground dealer in Czechoslovakia, and then hacked it into an EF mount. It also has the longest (and smoothest) focus throw of any lens I've owned. Here's the very first shot (the camera accidentally went off) -- I saved it just as a reminder of the hell I had to go thru to get that lens to work on my camera.

-- peer