I put this stuff on my mom and dad's '85 s10:
http://www.herculiner.comIt worked really well, kept stuff from sliding around. I didn't use the UV coat, so within a year it faded a little bit to black with a grayish hue. It still worked fine for many year until it was totaled.
It is fairly labor intensive, getting it clean and scuffing it up... I picked a pretty hot day so that the bed would dry out good, between the decreasing and what not.
I've seen the stuff sold in parts stores and at hardware stores.
You can read the instructions on the website and decided if it is something you want to tackle or not.
-W