http://groups.google.com/group/gimp-brushmakers-guild/web/file-license-recommendation
I've based this license on the one used with the Chaos & Evolutions
brush kit at David Revoy's site (http://www.davidrevoy.com/?article29/
free-brush-kit-for-chaos-and-evolutions). Some clauses are different,
notably, an exception that allows full compatibility with GNU GPL
(hopefully).
I'm not a lawyer, so this might not cover all the bases. Please
comment on it.
Happy brushmaking!