Field Agent is an app (Android and iPhone) that lets you earn cash by visiting retailers and performing certain tasks. A common task is an item price check with a photo. Another task is an audit/scavenger hunt (you have to find a certain type of product and how many are in stock). Pay is usually $3 and you have 2 hours once you accept a task. The app uses your zip code rather than GPS to find work near you. There are some "helpful tips" videos online.
After 5 days, I found 2 jobs within 3 miles. Jobs go fast and notifications are not pushed automatically to your phone.
Bottom Line: If you shop at big box retailers and enjoy taking photos, this is a good income stream.