4. Check in
Other social networking sites help you unlock discounts when you check in at restaurants, coffee shops and other stores around town, which is a main function of Foursquare. On one hand, Foursquare is a social review site: Like rivals Yelp, Urbanspoon and TripAdvisor, it's a trove of user-generated tips and recommendations. Looking for the best pizza in a new neighborhood, or a good, cheap hardware store? See which ones people have praised on Foursquare. On the other hand, checking in at whatever store or restaurant you're in — using the app's GPS capabilities — serves as a digital loyalty card; the more you use Foursquare, and the more times you check in at one particular place, the better the chance of being presented with in-app coupons for 10 percent off (or more) on your next pizza or coffee. What's more, Foursquare learns what you like to do and at what locations you typically check in. Over time, that translates to savings through Foursquare's Local and Promoted Updates, which you can access when you open Foursquare on your phone. If a restaurant in your neighborhood is having a special, you'll find out through Foursquare; if a store you frequent is offering discounts or coupons, Foursquare will let you know.
5. Pass the hat
Social media services typically have apps for mobile devices like smartphones and tablets, but there are also several stand-alone mobile apps that employ the collective power of your different social networks to save you money. Take SmartyPig, for instance, an online banking service that lets you set up a specific financial goal — say, saving for a long-delayed vacation or a new television — and share that goal with your Facebook friends and Twitter followers. Through those social networks, your friends can provide encouragement and even donate directly to your SmartyPig account. That means extended-family members can easily pitch in for a grandchild's crib, a kid's first car or your replacement dishwasher.
6. Make a big deal
Users of the online service Slickdeals can share information on ways to save money via a massive online forum. Slickdeals isn't so much a social network — it's more a Web-enabled savings community. With 18 different forums and 10 million users, the site gives you access to a sprawling network of frugal folks who post websites of stores promoting sales as well as coupon codes they've used. Use the search bar at the top of the home page, or check out the Frontpage Deals & Coupons. Clicking on any deal directs you to a page that explains how to cash in. It's free to join, and all the information is free to view.
7. Bring home the bacon
Finally, Grocery Gadget, a $2.99 download, works as a kind of miniature social network to use within your immediate family. With Grocery Gadget you can write grocery lists inside the app or on the free Web portal; your information syncs effortlessly with that of fellow smartphone wielders in the family who also have the app installed. Now everyone has the week's grocery list, and as items are checked off, each person will instantly know what's yet to be purchased. Reuse and update the list from week to week so you'll know exactly what you need, which should help avoid waste and allow you to shop more efficiently. You'll never find yourself coming home with too many cartons of milk.