coyote code has a decent roller if you're looking for offline. And there is an integrated roller in the board, though I'm afraid I don't have a link handy. I believe the basic mechanic on that is just [ roll ] XdY+Z [ /roll ] (without the spaces inside the brackets). You won't see the result until you post, so you may need to do a followup post or edit the description of an original, but it's definitely workable.