5' 1 1/2", 28" inseam (same as my DH, btw, who is 5'6")

165 mm MTB - a Santa Cruz Juliana Super Light (women's specific). I opted for the XTR group, but, the cranks/front rings of XTR at that time would have killed me, so mine are XT. They've got more XTR options now, 165mm crank length and compact chain ring....if I could justify the purchase, I'd totally option that up!

170mm road - came with the Shimano 105 group.

My Santa Cruz always feels better than my road bike, and I've never even considered if crank length is a possible issue. Now that you mention it, I think I'll ask DH to start Ebay hunting for me!!

I really like the fit, plus, I've been told the shorter crank also provides faster acceleration.

Ditto on the whole options for small people issue, though. I waited much longer than we wanted to for a full suspension MTB that fit me! At least things are improving!

Namaste,
~T~