AnalogKid at Random Nuclear Strikes has a mention of what looks like a great product with a lot of uses in the gun world. It's called Pac-Skin and it's made by Pachmayr. Here's the description from Midway USA's web site.
"Pachmayr Pac-Skin Multi-Use 5" x 20" Strip Black
A new generation of non-slip, sure gripping technology. This peel-n-stick rubber material provides the ultimate gripping surface. A finely textured neoprene rubber surface coupled with a "peel-n-stick adhesive backing makes a perfect accessory for your favorite gun, bow or any surface where improved cushion, grip surface or equipment protection are desired. Available in pre-cut sizes or in sheets for making your own custom fit. Black."
Here's Midway's page for Pac-Skin.