Some info :
Why should I use it?
Just as people can currently find out where some products come from and who made them (Is this banana organic? Does this milk contain growth hormones? Were these clothes made in a sweatshop?), it is important to have that knowledge for as many consumer goods as possible. Knowledge is power, and knowing where the product came from can (and should) influence what you buy.
The RIAA is a group of several hundred record labels. The roster of members changes constantly (major labels create new subsidiary labels, popular artists are given their own labels, artists or labels leave the RIAA due to creative or political differences, etc.) and it is almost impossible to keep track. Aside from memorizing the entire list, or having the list available and checking it while shopping, it is hard to know who is a member and who is not.
Why is it important to know if an album was released by an RIAA member or not?
That's possibly a fairly long answer, but just the highlights of the RIAA's practices involve price-fixing, blaming its poor financial state on unfounded digital piracy claims (and in turn, blaming and suing its own consumers), lobbying for changes that hinder technological innovation and change copyright laws, underpaying the artists it represents, invading personal privacy to enforce copyrights, and dismantling entire computer networks just because of their ability (of their users) to share copyrighted files. (Feel free to visit the RIAA and Boycott-RIAA.com to learn more!)
In order to successfully and efficiently support who you like (or not support who you don't like), you need to have information immediately available to know who is who. The RIAA Radar works in two ways: if you're looking to stop buying RIAA releases, it will help tell you what albums to avoid (or purchase secondhand); if you are looking for new music or new alternatives, it works to promote non-RIAA releases by providing similar RIAA-free albums to almost any RIAA release, and RIAA-free popularity charts for several genres in order to showcase viable alternatives.
How does it work?
When you run the RIAA Radar, it uses Amazon Web Services to get the album information. It then checks the record label data given by Amazon against a local database based on the official list of RIAA members (but heavily added to beyond that), and returns the result based on a match.