Craigslist (by Lifelike Apps, Inc.): Free for iPhone/iPad
Craigslist.org has become one of the leading sites when it comes to buying and selling used and new items, finding an apartment, getting a job and more. Several developers have created Craigslist apps, but the version by Lifelike Apps leaves the competition far behind. The interface of the app makes Craigslist look like a regular newspaper, whose classifieds section you can easily filter by location. You can even circle listings with your finger. The app makes selling equally easy, allowing you to add photos directly from your Apple device's gallery, as well as enabling you to reply to interested buyers directly through the app.
Craigslist Mobile (by YYH Creative): Free for AndroidSimilar to the Apple app, described above, the Craiglist Mobile app lets you search listings and post your own, with photos. You can also contact buyers -- both by phone and by email -- right from the app. The interface is simple and straightforward, though it doesn't share the newspaper-like layout of the iPhone app.
Zaarly: Free for iPhone, AndroidZaarly allows you to request and provide services within your local area in addition to buying and selling goods. Whether you are looking to sell a couch or market your services as a dog-walker, you can easily make some extra money when someone responds to your ad. If you are looking to buy items or receive services, such as, say, help cleaning out the attic, the app can be equally useful. All you need to do is click on the "request" button. Results can be displayed on a map and filtered by price and date. This way, you'll keep clear of irrelevant results.
iGarageSale: Free for iPhone, AndroidNow that you've made room, you may want to pick up more stuff for your home. While garage sales are often publicized via posters and word of mouth, you can also use the iGarageSale app to find sales near you. Results are displayed in map format, making it easy for you to map out your route to the nearest event. You can also search by date and the type of goods that will be sold. The Pro version ($1.99) lets you search for specific items and save favorites.
More efficiency apps: