For myself, I find I can do almost all my work on my ASUS Eee Pad Transformer, a 10" Android tablet with keyboard dock; so much so that it's become my primary machine for most things (which I certainly didn't expect when I got it—I picked it up second hand at around a third of the regular retail price; I never would have paid full for it with my expectations of it at the time). It's got a decent keyboard and marvellous battery life.
Most of my work is done in Ubuntu, installed inside Android via Debian Kit (http://sven-ola.dyndns.org/repo/debian-kit-en.html). From a terminal emulator, I can then run proper versions of Vim, Python, Mercurial, etc. as required, and have it all just work marvellously. (Before going with Debian Kit, I'd had clumsy parboiled editions of Vim, Python and Mercurial.) It's great for web development. Not a particularly speedy machine (the TF700 or even the TF300 would be considerably better than the TF101), but quite sufficient for most things.
