NoBoard
Keywords: Variant
We once tried to play without a board. Just on a wooden table directly.
The most difficult task here is to calculate whether a ladder works or not.
But you also have to remember which point the different stones are on in every corner
Two pictures from Tuchola (PL) Go Congress:
(bigger: http://matthieu.walraet.net/go/tuchola2004/big/349-4922_IMG.JPG)
(bigger: http://matthieu.walraet.net/go/tuchola2004/big/349-4923_IMG.JPG)
Also see: Go On A Board Without Lines, FreeGo