If Match.com and Foursquare had a baby, they'd produce StreetSpark, an app for your iPhone, iPod Touch, and iPad that helps you in finding a date on the go. This free app combines the location-based fun of social networks, and the personality-matching methods of modern dating websites to introduce you to like-minded individuals around you that have the same interests.
Just fill out your profile online, then fire up your app to see who's nearby. See someone you like? "Ignite" them to let them know you're interested! You can even use your iPhone's camera to enable an in-app augmented reality feature to pan around your location and see who's around you right now. Kinda creepy, but also kind of convenient if you're in desperate need of a date.