I was under the impression that FWD hybrid systems were allowed to collect energy below 120 km/h, they just were not allowed to release it below 120 km/h.

Not a full computer, but there's always the Apple IIe card for the Mac LC.

The Acorn RiscPC isn't rare in the UK, but it's incredibly rare outside of the UK (I know of three here in the US, I'm sure there's more, but most likely double digits), and certainly an interesting one, as far as its architecture goes. (And the OS makes some interesting UI decisions, too.)

Other interesting platforms to consider:

PC-GEOS-based systems, ranging from the Brother GeoBook (a predecessor of today's low-cost netbook) to the Nokia 9000 and 9100 Communicator smartphones
Speaking of smartphone platforms, the IBM/BellSouth Simon, the first smartphone
Sharp X68000 and X68030, Japan-only platforms that received some of the best arcade ports out there