Are any of you using any iOS iPad apps to control Ableton? If so, which ones are you guys using?

Yes, Touchable is brilliant. I stopped using my Launchpad because of it.

I am using touchable as well, very solid and well integrated with Ableton. I would love to give the Lemur app a go but 50 bucks is a pretty penny.

I experimented with a number of iOS ableton controllers, and the $50 for lemur and mu are absolutely the best. It may be software, but it is still cheaper than any APC or Novation device out there...well worth it.