I am trying the Colemak keyboard layout because it seems to be a lot smarter than qwerty. Requirements of keyboards have moved on since the days of typrewriters...
Colemak seems to be a good candidate because it minimises the number of changed keys to make it easier to switch between the ubiquitous qwerty and Colemak.
To test my current speeds as a benchmark, I used an online speed test.
On 2 February, 2010, My qwerty speed was 61 WPM, and my Colemak speed was 9 WPM, while using the on-screen keyboard as a guide.
On 3 February, 2010, my Colemak speed was 10 WPM, without looking at the keys.
On 7 February, 2010, my Colemak speed was 15 WPM.
On 8 February, 2010, my Colemak speed was 19 WPM (with one mistake: missing the second 'e' of Hernecastle).