We bought a small math-and-dice kit awhile back from Scholastic (Math on a Roll: 10 Wacky Number Games, from CB Products Inc.; I checked their website but it doesn't seem to be in their catalogue anymore). Since Ponytails is doing fractions right now, I found a fraction game in there, called Pizza Parlor, that we played today. You could play it even without the special fraction die that comes in the kit.
This is how you play: each person draws a circle on a piece of paper, and divides it into twelve sections. If you have a die marked with fractions, you roll it and draw/colour toppings on the sections of your pizza that match what you rolled. If you roll 1/2, you draw toppings on half the pizza. The fraction die we have includes 1/10 and 1/100, both of which don't work, so the instructions say if you roll that, you lose your turn. You don't have to match the amounts exactly to win: the first one to colour in all (or more) than their whole pizza wins the game. We played this about three times this morning and that was our math lesson (including discussion of what 2/3 and 1/4 of a pizza looks like).
If you don't have a fraction die (or don't have a blank one to customize), you could still play this by making up some small cards with fractions on them (anything that would work with the 12 sections on the pizza, plus a couple of "lose turn" cards). Then just take turns drawing cards.