My initial plan was to allow each investor to choose their own house edge and risk level and have them form a market like on an exchange, so the player gets matched by whichever investor(s) are offering the lowest house edge(s).  This would result in competition between investors to get gambler action and cause the edge to be the lowest available anywhere.  I wonder how such an idea would go down.  It would probably result in a few crazy investors offering very low edges, and leave the sensible investors getting matched by none but the biggest bets.  (Like how when you ask for more than the current market rate on MtGox when selling coins, you only get matched by the big buy orders).