Like Instapaper but for physical locations, Matchbook saves locations you want to visit for another time. If you see a restaurant you like or a cool shop you want to remember, you can simply open Matchbook and bookmark it for later reference.
Matchbook's interface is very simple: you just tell Matchbook you're currently walking by the location or you type in the name of the place you want to save. It'll provide you with a list either way, you choose the option you want, and then save it as a bookmark with any relevant notes.
Matchbook will then keep that list handy for you and categorise it by its general area. That way you can visit next time you're looking for something to do in that part of town, or make plans relevant to where you're headed. It's a pretty simple but certainly useful app, and you can pick it up in the App Store right now for free.
Matchbook (Free) [iTunes App Store]