IRC chats off-site use bots to "roll" although there are plenty of allegations of cheating as these bots can be rigged to always roll higher than what the other person rolls. Not to mention any hosting fees you pay, and you're pretty much guaranteed to not make money off dicing
Basically you go into a dice channel, say #dragondyce, and you place your bets ingame with the hosts ingame. The host create a duel and basically all you need to do is type !roll, winner gets paid, loser doesn't.