I like the idea of a poker-style tournament system for 100 player games:
1 - You ante-up a fixed amount of gold as an entry fee. No gold use is permitted.
2 - Winner wins 90% of the total ante, 10% goes to the house as a rake.
Incidentally, with the option of gold use removed CoW can be proven to be a game of skill, not chance; thus byassing US federal laws against gambling... but that is a bit of a side-track.