Eat-a-Rama is basically a google maps mash up that combines restaurants & bars with google maps. It also throws in a social networking component into it and slick AJAXy interface. (It also shows alot more restaurants with clustering and what not on the map than vs the lame '10 random search results' that google maps gives you) I just recently created from start to finish the iPhone twist which gives you a list of restaurants close to you and an ability to filter them by name/tag/address/whatever. You can also call the restaurants or get directions. iTunes link:
http://www.tinyurl.com/eatarama