This guy might be small, but he squeezes in a 3in scratch-resistant display and a QWERTY keyboard. Neat. You can grab the Sony Ericsson Xperia mini pro on PAYG from O2 for £129.99.
Just to be clear, this is the newer mini pro model, not the x10, so it has a larger display, 1GHz processor, and runs Android 2.3 (Gingerbread).
(Thanks to Neostar at HUKD)