Rob O'Donnell wrote:
 Even sillier...
 I'd like to see someone build a replica of HEX, from the Terry Pratchet
 Discworld books - from the descriptions, it's digital computer that
 operates via ants running around tubes..  (I guess, get them a fine enough
 bore so that the ants couldn't turn around, you could get it to work...)
 Rob. 
Don't forget the computer built from tinker-toy parts (wooden hubs and dowels) at some
university in, IIRC, the early eighties...