With the Holidays just right around the corner this is the time I have found that a lot of survey companies push their product research. I love testing products, it's a lot of fun, you get the product for free and after you completed all the requirements you get compensated. Here are some companies that I participated in many product reviews.
Mindfield is super simple to sign up with and I get at least two surveys from them a day
Toluna is also a great company they also send out a lot of surveys, they offer many high point surveys which can be redeemed for cash and other prizes.
Synovate is a great company to work with also. All the product testing I have done with them I have received full size samples.
I'm looking forward to another great season doing product reviews. (I am not saying these companies don't offer product reviews any other time of the year. It just seems like around the holidays it picks up)