Sites come and go... you should check out several and decide which ones you like. Some are very minimal, and others are extremely detailed. http://www.roll-dice-online.com/ http://rolz.org/ The above might give you a few ideas of what you're looking for. I found a lot that were only for d6 but if you need other kinds, those won't work. This is the site recommended to me by a friend who's running an old-school AD&D game: http://invisiblecastle.com/ Just at first glance, it looks pretty decent.