Some of the examples of things that I have tested are, Gillette Fusion blades before they were public, Schick Quattro Blades, Hanes T-Shirts, A new Cap'n Crunch type of cereal from Kellogs, a new flavor of beef jerky from pemmican, and many more.
The best part about testing these products, is after you are done testing it, you not only get to keep the items, you often will get paid as well. Many of these product tests I have done have offered me $20 for testing the product. I have been an active member of online survey panels, online survey clubs, and I am a member with over 20+ online survey websites. Some of these market research and survey sites offer surveys for your opinion which they will compensate you for with cash. Others will send you products and have you rate them, for which they compensate you with the free product, and now and then, they give you both the cash and the product.
I really enjoy testing out the new products and giving my ideas. I always see new commercials for products, especially men's razors, and wonder if these are any better than the one I am currently using, luckily for me, since I fit in the category for market testing these products, they often want my opinion of these, and I get to test them. I have friends that I have got started on surveys that get to test the newest make up as well, and they love it. Product testing is huge and extremely important and beneficial to the companies. These companies need honest opinion and feedback from the end consumer and they are willing to pay for it. All of the survey companies will now and then send you surveys about product testing, however there are some sites that specialize in it. If you are interested in taking surveys but you are not too interested in just taking surveys for your opinion, then these are the sites for you. I personally like to sign up for all of the sites and after a month or two if I don't like the types of surveys they are sending me I just cancel.