I've started working on a webapp version of Sic Bo, a.k.a. Big Small, which is a Asian dice-game. It's one of my wife's favorite games and I didn't see many options out there to play this game. It is a game like roulette or craps where you bet on the outcome of a roll of 3-dice. There are various options for betting.
Wikipedia has an excellent description and sample board.
I has a road map in mind for development, but I really want to push a very simple nuts-and-bolts version within the next couple weeks. For development, I will be making extensive use of the PEAR libraries, especially DB_DataObject, which is one of my favorite data object libraries out there.
I am thinking about making a really glitzy interface in Flash, as that's half the fun of casino games, but I definitely want to have an option of interfaces, as this will be a good game to offer mobile users.