I love to bake. While I have yet to master the secret of chewy, not-too-crispy chocolate chip cookies, I HAVE found the secret to not burning the bottoms: Parchment Paper.
Parchment paper is a baking tool used to line your cookie sheets and baking pans. It helps eliminate the need to grease the pan (I have seen recipes call for you to grease the pan, line with parchment, then grease the parchment - those cakes popped out like a dream!). It creates a non-stick surface and allows foods to cook more evenly. While I use it primarily in baking, parchment paper can also be folded to make moisture-resistant packages for cooking "en papillote" - essentially steaming the contents when placed on a grill or in the oven - perfect for those looking for a healthy, low-fat method of cooking. Here's a sample recipe that has my mouth watering.
You can buy parchment paper at fancy online shops, but I buy the Reynolds brand at Wal-Mart. I can't recall how much it is, but I only buy about 3 rolls per year. If you visit their website, you can print out a coupon for $0.75 off.
Note: Parchment paper is a disposable version of the Silpat or silicone baking mats. I've used baking mats before, and I prefer parchment paper because I think the baking mats are a pain to clean.