I participate on a website called Crowdtap. What happens is companies will ask questions for people to answer, and as you answer them, you build points and reputation with each company. At the end of each month, each company, or each "brand" as they call them, has a drawing for multiple gift cards (usually for Amazon); every 100 points gets you an entry.
They also do what are called "Sample and Share" parties. The companies send you a sample of a product for you to try, and share with friends, then review on the Crowdtap website. I was accepted into one from Puma (free pair of sneakers), one from Schick (free razors), and one from Truvia (free natural sweetener). In the past I was given a free Windows 8 phone from Verizon, which you could keep, and I traded it to Gazelle.com for like $175 or something.