Mechanical ergonomic keyboards?

I'm looking to replace my beloved Unicomp On-The-Ball, because the buckling springs are a bit too noisy for the open-plan office in which I'm working. The Unicomp will take pride of place on my desk at home, though :)

Can anyone on HN recommend a mechanical ergonomic keyboard? The only one I've found is this:

http://www.trulyergonomic.com/

... but the manufacturers haven't yet replied to my email, except with an automated response apologising for delays resulting from high levels of interest.

Ideally, the features I'd like would be:

- Cherry switches (pref. brown) - ergonomic layout - integral trackball / trackpad - custom keycaps to swap Ctrl and Alt - custom keycaps to replace the Windows logo with Tux, or similar

Only the first two are essential, which is why I'm so interested in the Truly Ergonomic keyboard.