I am also looking at rug pads. I see a variety on Overstock, but some people complain about their chemically smell.

I saw those as well delta -- hopefully someone with more experience will give us guidance!

rug rag has an evaluation on some of the common types available.

Here is a link that might be useful: Rug Pads

Here's a great video someone (Allison?) posted a while back.
Dee

Here is a link that might be useful: Rug pads

Thanks for your help -- anyone else?

Most rug underlayment is one of two types: PVC or synthetic fiber. PVC works great for non-skid situations, but if you are looking for some protection for the rug, I think the synthetic fiber is a better choice. This type of underlayment is usually stocked in roll form vs. pre-packaged sizes. Your best bet for finding these locally would be at a speciality rug dealer. I work for Mohawk Carpet and we make a fiber style underlayment in two versions called Rug Assist and Rug Assist II. Both are brand new, so they may be hard to find just yet.

following up -- I ordered one from Overstock and it's great - laid out flat, no smell, stays in place

I got mine at Homegoods. Very slight chemical smell at first, but gone within a matter of minutes after unrolling it and laying it out. It is a spongy, mesh sort of pad. Worked out great for us. I think it was $39 for 8x10.