The last few times I've been to my climbing gym, I've worked problems on the slab wall. Slab climbing is (usually) a climbing on a pretty flat wall with a positive slope (leaning back, not forward - so it's not overhung or vertical), and pretty small hand and foot holds. Until I tried it out, I never would have guessed that I'd enjoy or be good at slab climbing, because super small crimpy holds are difficult to get used to.
I tried out a few of the problems on my gym's slab wall and found that I wasn't awful! I definitely wasn't phenomenal, but I was able to hold my own, climbing a couple V4's on the slab. Two of the biggest challeges with slab climbing (for me) are maintaining and trusting my balance, and trusting my feet on super tiny jibs. I struggled with one problem where balance was critical to standing up from a horizontal position where the top hand is on a crimp and the bottom was a mantle. I almost didn't finish another one where both feet were on tiny jibs and I had no choice but to trust them, as my hands could barely hold weight on some tiny crimps.
I don't have any good photos of the slab wall at my gym, so here's a photo of someone slab climbing outside in England (credit http://climbing.com):