- Foursquare — The current king of geo-location apps, participating Foursquare businesses can offer deals and discounts for mayors and frequent visitors, ranging from free frapps at Starbucks to 25 percent off at stores like Sports Authority.
- Loopt — Loopt has been known to offer an automatic 25 percent off purchases at Gap and deep discounts on Virgin America flights, and even show you available rewards near your current location. Now it's even integrating Groupon's Groupon Now deals into the app, so you can find great deals on the go.
See the rest of the list (there's quite a few) after the break.
- TopGuest — An emerging membership service, TopGuest, lets you choose which location-based app you want to use — be it Foursquare, Loopt, Gowalla, or others — to check in at various locations and earn points. TopGuest has partnered with the likes of Starwood Hotels, Delta, Virgin America, and Instagram, so it's a good one to have on your phone if you're a frequent traveler.
- WeReward — WeReward actually pays you to check in at businesses in your town by issuing "Rewards Points" for each check-in or completed task, which are worth a penny each. After you verify and claim check-in rewards, cash is sent to your PayPal account, where you can rack up the points and make a few bucks in the process.
- ShopKick — You can earn ShopKick rewards just by walking in the door of many big-box stores (like Best Buy, Target, Macy's, and Crate and Barrel), and activating your ShopKick app. What do these rewards get you? Well, collect them to get free items, or earn discounts by taking pics of designated items.
- Google Latitude — More than just checking in, Google Latitude is adding the layer of "status" to its check in rewards program — the higher the status, the better the reward. So keep checking in to stores like Macy's, Radio Shack, and American Eagle (with more to come) to get the best deals.
- ShopAlerts — Currently available in New York, Los Angeles, Chicago, and San Francisco, ShopAlerts texts you with special deals and offers when you're near a participating retail location. There is no cost to join, but of course, normal text message fees do apply.
- Gigwalk — This app allows you to perform "gigs" at local businesses (like taking pictures of menus, food items, document venue, or store information) and earn a few dollars for your time. It's like getting paid to explore your city, and what can be better than that?