Small workbench drum sanders ?

[EddyCurrent]

This can be bench mounted but maybe bigger than you want.

http://www.axminster.co.uk/jet-10-20-plus-drum-sander

I once made a jig to use a small oscillating bobbin sander, the workpiece was fed in on it's side. It was basically a hinged piece of plywood with a threaded rod adjustment so the gap between the drum and the plywood could be adjusted. Obviously the workpiece was then fed into the gap.

Like this

http://www.stewmac.com/shop/Tools/Sa...g_Station.html

I also remember seeing someone build a machine like you mentioned using a hand held belt sander in a jig.