Those Golfsmith type mats are fine for a driver and even fairway woods, but I worry about using those relatively thin mats for irons; seems like a good iron swing would want to chew right through the mat, failing that it would be hard on the wrists.
I tried using an old bathroom rug last night; it's now shredded.
The Flextee looks like it would absorb some of the shock (I'm a sucker for infomercials).
Only one range near me uses mats, all the others use real grass, and they look like that were attacked by hordes of giant divot eating locusts. I'll check with my pro and see what he might have for sale.