What you do is get your map, enlarge it somewhat, use some software to mirror it, print it out, and put it up in the windshield. I'd use Paint Shop Pro, but you can use whatever you have that's capable. I don't think the map would do me any good (other than giving me a headache) but I think turn by turn directions in a large font that were mirrored would do just fine!
Some commenters have some improvement suggestions as well!
This is almost luddite like in it's execution!
Here's a sample! See the full size on my flickr account!
The reverersed version!
Question: Should I have put this behind a cut?