I came across this awesome set of instructions for how to make an incredibly thin, waterproof hiking map! The end result of this simple project is a 100% plastic map that is thinner, lighter, and more durable than paper.
This project is great for hiking familiar areas, when all you need is a quick glance to make sure you're on track.
It's not good for unfamiliar areas, or should only be a backup for those situations, because of some limitations of this technique. Plastic film shrinks when heated so, the map scale will no longer be correct (i.e. a 1/4 inch will no longer equal a mile, etc.) Also, the fidelity of fine map details may be difficult to discern. Printer ink does not absorb into the plastic film so, the surface tension of the ink will will blur small text and fine details. There are ways to fix this (according to the comments on the ible) but none of them seem truly worth the effort!
My suggestion: bring a real, master map in a ziploc bag as usual. Make one of these as a back up, or for when you're just going out into very familiar territory.