I ran a casino for awhile called Mandalaybay, with the Casino guild tag. It can be very profitable, but anyone who remembers mine knows that I gave almost everything away to random people through /roll contests or whatever.
I did roulette as my main starting game, with actual casino odds. /random 0 37, 0 and 37 being the house numbers 0 and 00. You could play it just like regular roulette, combining bets etc. Betting a number and hitting it paid out 35x, and I paid that out many times while I was running it. Most people just played even/odd which was far and away the best odds casino game on the server at the time.
The casinos that do the 550+ games, with 990+ only paying out like 3 or 4x the bet are just obnoxious. Having to hit a 1/100 to get paid out 4x? Ridiculous.
Over time, I had a LOT of action and make a few hundred k in plat. The keys are that you need to start with a decent bankroll and be ready to absorb some losses.
But in the end, the house always win.
EDIT: Oh, and I also ran this:
http://www.project1999.org/forums/sh...ight=powerball
Ended up being pretty successful and fun.