Garage sales are not only a good way to buy local, but also to recycle goods for cheap prices. You can always check Craigslist or the top of your streets for signs of nearby garage sales. iGarageSale for Android and iOS ($1.99) pulls garage sales from Craigslist but then shows them on a map that lets you bookmark your favorites and make your own map of places to hit. Etsy also lets you restrict the goods you're looking for to local craftspeople.
Local services are likely the easiest thing to find, even if you don't have a farmers market near you or a lot of garage sales. A quick look through Angie's List or the Yellow Pages was the traditional route. Now Yelp, Gowalla, Foursquare or Google Maps is enough to produce some names. Getting plugged into this community is important, from maintaining the listings of local shops to giving them good ratings. Another way to support local services is using local deal sites. Not only Groupon, but even one more region specific like DealMobs (Southeast) or ZapHour (Portland) or deal-type specific ones like Jewpon (Kosher). Even individual communities (like Santa Monica) are banding together to make local deals and listings. If you can't find what you want nearby, or just want to support the country in general, the Made in America ($.99) app will tell you based on the bar code whether or not the good you're holding was made in the U.S.
Do you buy local? How do you help keep your community alive with your technology? Share you ideas in the comments.