Those pedals and other pieces of gear that only do one or two things, and that have virtually zero use in everday musical situations, but you still find yourself drooling over...list 'em!!!!
MXR Blue Box. Despite the crappy tracking and so forth, there's something I find perversely fascinating about the tone.
Guyatone Wah Rocker. After watching a vid of Guthrie Govan messing around with this thing, I'd really like to give it a go, mainly for percussive noises.
Digitech Synth Wah. Mostly for the synth and talkbox effects.
Boss RV5 Reverb. Solely for the modulated reverb setting. On the list due to it being fairly silly spending that much on a pedal for one tone which wouldn't get much use.
Digitech Space Station. Mostly for making epic sci-fi noises.
Yamaha UD stomp. It's a pity this thing never took off, as it was stupidly well-specced, and sounded amazing.
Boss Space Echo. The Line 6 DL4 is much better bang for your buck for this sort of thing, but I really like the tone of this, and the way you can do Tommy Bolin-style echo-wooshes without taking your hands off the guitar.
Line 6 Purple pedal. Same reason as the Space Station.
There, that got me off for a few minutes. Fire away!
I've always been fascinated by ring modulators. I can never get anything but horrible, wretched sounds out of them, but I keep trying. I used to have a DOD Gonkulator Modulator (and was very happy to find it cloned in my gsp1101). I've always wanted to try a Snarling Dogs Mold Spore Psycho, a ring modulator/wah pedal.
In total honesty, I don't even know how a ring mod is "supposed" to be used - but they make a screeching racket.