The HHKB (on which I type this) is kinda minimalist but it's still a "60%" keyboard (no numpad, no functions keys and no arrow keys for the HHKB but some 60% have dedicated arrow keys). There are people who have custom 40% keyboards (you simply use a modifier to access the "missing" numbers row).

The most minimalist has way less keys than that and is probably the DataHand (or something close to it, like a one-handed DataHand if such a beast exist?).

I like the look of the keyboards he realized, reminds me of the ErgoDox. Not that contrarily to the HHKB the keyboards in the blog aren't "staggered" and are all split. The HHKB appeals to many because it has incredible switches (Topre) yet stays very close to traditional keyboards that people have been using for years and years. It's not easy to adapt to a non-staggered layout and some people are allergic to split layouts.

If you're into that sort of thing, GeekHack.org and Deskthority.net are good places to hang out on.