I have all kinds of odd adapters.
Re: FD-EOS, I use 35mm mostly for bird photography, so almost exclusively with long lenses, so when I found a good deal on an original FD-EOS converter (only works with 200mm and longer due to protruding lens elements and acts as a 1.2X converter) I bought one. I also picked up a rare Tamron Adaptall mount for EOS, since I have a couple of those lenses as well. I'm confident that my F-1N will be good for another 20 years at least, but somewhere along the line, I can see looking into a digital body, and I don't want to get stuck having to replace my FD teles with EO$ versions.
I also have an FD-Bronica S adapter for macro, that Frank Marshman made for me for about $50. In the macro range, FD lenses like the 35/2.8 Macrophoto and Tamron SP 90/2.5 cover 6x6 with no problem and are really sharp.
Went through an M42 phase, but didn't find any really unusual lenses that I really liked and didn't have perfectly good FD counterparts. I still have the adapters though, just in case something comes along.
I wrote a piece on lens adaptations for usefilm.com, which you can read here:
My favorite 35mm adaptation has been the Ektar 100/3.5 Medalist lens, for which I cobbled together an FD adapter. It's a Heliar type that's great for portraits. You can read about that one here on Bob Monaghan's site, which has lots of info on lens hacking, particularly for classic Bronicas: