There are a variety of styles of laptop platforms, some powered, some not. Several years ago I got the Targus Notebook Chill Mat, a USB powered platform. It has the same horizontal dimensions as my Dell D600, and is about a half inch thick. It has two fans that pull heat off the bottom of the laptop and blow the air out the back,
I paid $30 for it 3 years ago I think, and I didn’t really expect it to last this long, but it has. I don’t use it in the winter, I enjoy the heat on my lap, but in the summer it’s unbearable. I slide this underneath and I don’t get any heat on the bottom.
If you’re looking for something like this, I’d recommend this one. I don’t know if it’s BETTER than any others, I’ve only ever used this one. But this one appears to last.