If you're into boardgames and/or RPGs, then why not try BBQ DiceKit - a quick and simple to use dice rolling utility that serves as a good replacement or backup for your physical dice. Features include the regular six-sided spot dice, colour spot and logical dice, poker dice, plus eight RPG dice: d4, d6, d8, d10, d12, d20, d24 & d30. If you think this would be a handy thing to have on your Nook, then you can find it here: http://www.barnesandnoble.com/w/dicekit-bbq-games/1117992137?ean=2940147172445

Please note that the free demo version has enough features by itself to serve as a standalone app if your tabletop gaming needs aren't that intensive. All that's missing in this version are the d24 and d30, the ability to make custom dice sets - oh, and there's a few ads to put up with. But that's all. Otherwise, it makes for a pretty good freebie.