I loooooove free samples, and I also love marketing techniques.
Give you my hotmail address and you'll give me a free sample? You got it.
I frequently visit a couple of websites in my quest for free samples, and I am continually amazed at what is available (granted, I am easily amused). Some of my best finds include a free bag of Feline Greenies and an invitation to join the Nike product testing panel. (I'm not a runner, so I sent the latter to a friend of mine -- she received prototype Nike shoes in exchange for her feedback!)
I really love it when companies send out entire kits to consumers for marketing purposes.
For instance, a couple of months ago I received this:


It's a taste test for Diet 7up. They sent me a box with a can of Diet 7up and cans of two competing drinks, plus a 7up coupon. The theory is that they are so confident I will love Diet 7up, they want me to compare it directly with the competing drinks.
I recently received this box from Del Monte and Starkist:


I went to a website sponsored by Del Monte and Starkist and made a pledge to start living a healthier lifestyle (which really is one of my goals). To "help me in my journey" or something, they sent me an "I Pledge" kit containing a pedometer, a support bracelet, a pack of tuna, a pad for grocery lists, and a booklet with recipes and coupons.
The thing is, once I receive the samples, I feel almost obliged to try them. I'm not really a tuna fan, but since Starkist sent it to me for free, I'll at least give it a shot. So I get free stuff, and the companies get me to try their product. Works out nicely for both of us that way.