1 - Which camera do you have that you find yourself using a lot more than you ever expected, and what about it surprised you?
I was just getting into digital when I scored a T90 and 1V via ebay, thinking they'd be shelf queens. Today the T90 is my most-used camera, followed by several EOS. The 5D has been gathering dust for a couple of years now. Can't say I'm surprised by my love affair with it, the T90 was my first real camera way back when, used it in photography classes, took it on road trips, etc.
2 - What camera did you get that just hasn't worked out to be used as often as you planned, and why?
RB67. Beast of a camera. I've had mine for two or three years now, and I've put just under two rolls through it. I've never been a tripod kinda guy, so I just wore it around my neck. It worked out pretty well, but there's always something I'd rather use, so it stays at home. No plans to sell, I just have to make up my mind to use it.