Here's something I figured out at work today...
Hypothetical situation... say you have a HP Color Laserjet 2605dn... and it keeps reporting a paper jam because it's not picking up paper. Your first thought should be pickup roller (or that little pickup assembly thing in the paper tray).
Sure, you can go buy a new roller for like $15 after shipping. But where's the fun in that?
Conveniently, HP has provided an animated guide on removing/replacing this roller for you to start with (click Remove/Replace/Assembly, then Pickup Roller). So pull out the old roller and have a look at it. You probably will see a very smooth surface on the rounded part of it. While inspecting the roller, you should also notice that it's more of a "half" roller in that it's round on one side and mostly flat on the other. The flat side does ever get used, just the rounded side. That's the part that picks up the paper.
Here's the good part that will save you some money and hassle. Just remove the rubber part from the plastic roller, rotate it and put it back on. If you rotate about half way, you should expose the unused part to the rounded side and be able to just reuse the same roller! You're good to go for another... well... as long as the first side lasted anyway.