To me a keyboard is a keyboard is a keyboard. Back in the day I actually had a USB keyboard running through a variety of adapters to fit it into an old-style keyboard port (not ps/2... before that). However one mouse I loved was this thing called the Q500, though not often listed under that name on ebay and there are clones.
Here's the Q500 itself, with its mousepad:
http://www.ebay.com/itm/OPtical-Laser-Serial- … 119.m1438.l2649
And here's one of its clones:
http://www.ebay.com/itm/D-Serial-Optical-3-Bu … 119.m1438.l2649
You can probably see what made it special to me right there--my old comp used to be limited to 9-pin serial mice, and for a long time I thought optical mice didn't exist for serial ports. When I found this guy I was happier than Scooby with a box of Snacks. Of course I later found other things like this but which tended to be more expensive, and eventually I moved on to a comp with ps/2 ports, but I'll always have a soft spot for this guy who saw me through some dark times.