I've used b-quiet extreme (bottom of the line by brownbread), pretty cheap, easy to put on, no smell...and it even cuts down on road noise.

In addition to the links Hans provided for Dyanmat alternatives, here are a couple more. Both are the new liquid with ceramic additives. Formulas for both sound and heat available at quiet coat. Haven't tried them personally but a local shop uses the ceramic paints in a lot of cars. Can be sprayed with special sprayer, rolled on, or brushed on.

http://www.quietcoat.com/index.html view their comparison video

http://www.coollizard.com/

I've used mostly Dynamat since I can get it locally. The new extreme is the only thing to use in the Dyanmat brand. Most expensive but worth it. Other brands have similar and is usually the top of the line. As much of a pain it is to install, especially near 100% coverage, I wouldn't waste the effot for a less than maximum dampening product. Next dampening project I plan to try the ceramic "paint" to see how they do. Anyone out there tried the ceramic paints?