One Friday night for fun, I pulled out 4 notecards (just inexpensive notecards I had picked up) and asked each one in my family to pick out a product that they liked. I then said we needed to let the companies know how much we appreciate their product. Then we each wrote a little note to the company. I looked up mailing addresses via the Internet, and we mailed them off. Then, the real fun comes later when these companies send you a letter back and often have a coupon or two enclosed...sometimes even for free stuff.
Here's what my 10 year old said: "Dear Keebler, I really love your cookies and for a while you put transfat in them but now your getting better. So yeah!" and my 12 year old wrote to Doritos and said he really loved Cool Ranch Doritos, so keep up the good work and one time he only got 3 chips in a bag, then he added: "I'm not here to complain...I just wanted to let you know so you can fix that problem".
This really works for me, if you want to see what works for others, head on over to Shannon's blog for all sorts of great tips!!