I've worked with 2, 4, 5, 12 and 15 and can tell you that they do send the products they promise. I'm definitely going to be signing up for more of these.

1. Tomoson - Product Review site for Bloggers. You will need to have social networking accounts as well since there are requirements set from different advertisers. I have gotten my foot in the door of product testing with this site.
2. BzzAgent – Fill out easy one page surveys and qualify for campaigns.
3. Influenster - Receive random Vox Boxes if you qualify from the surveys they send out.
4. MomSelect - In-home parties to test kid products
5. House Party - Test products and have in-home parties.
6. PinchME - Get new samples to try out every 2 weeks
7. Smiley360 - Free samples of various items
8. Kraft First Taste - Try new Kraft food products
9. Vogue Insiders – Try new beauty products
10. Tide Team - Try new Tide products
11. Pillsbury Mills Advisory Panel - Try new Pillsbury Products
12. All You Reality Checkers – Test products for women
13. Nike Product Tester - Apply to test shoes and apparel
14. Generation Mom - Test kid/baby toys
15. Moms Meet – Test kid products with a group of your friends/family
16. InStyle Trendsetter - Evaluate brand-new products!
17. Marie Claire -  Exclusive access to special offers, insider events, sweepstakes, and more.