The Google Shopping Content Objective-C Library by Google can access API data to sell products on Google, list ads, drive traffic, and increase sales. Developers can interact with the JSON API, working with iOS 3+ and Mac OS X 10.5+. Available introduction and example applications.
Covering over 200,000 foods and dishes, MyNetDiary's API provides two services to integrate right into your application: FindFood ( 0.5 cents a query) and GetFoodDetails. The input format is HTP request parameters or SOAP. Output format is JSON or SOAP. Food lookup results are sorted by popularity.
The daily deal space is hot, and has been for some time now. In the past year 23 million Americans have purchased a daily deal or group coupon according to a survey conducted for the American Institute of CPAs by Harris Interactive (source). Not to mention Freelance websites, such as Freelancer and Elance, have been flooded with thousands of "Groupon clone", "daily deal site" and related job postings - a general sign that many more businesses are still trying to get in.