A while back a friend of mine asked me questions about how to determine the probability of drawing card combinations from a deck, specifically for Magic the Gathering decks, and I created a simple Monte Carlo code to answer his question. I said I'd eventually create a nice Windows95 version for him, and I've finally got a rough version ready.
I figure the next thing to add to this is some sort of Either/Or draw probability, say you want to play a B2 card by the third turn, and have swamps and mountains in your deck, and want to consider getting one black and 2 of either a red or a black mana. I'm not sure how I'm going to do this quite yet. When I have time, I'll think about it some more.
Try it out, let me know what you think. If you are interested in fun applications of Monte Carlo codes, also take a look at my darts page!