My employer recently had the body & paint done on the welding truck I drive. From the body shop, it went straight to be lettered, by airbrushing. He also had planned on having a mural done on the hood. Since I'm the only one who drives it, he asked what I would prefer. Naturally, I replied "Something skydiving related" since that's my obsession, at least from May thru October.
With the help of some photos for ideas, and thanks to the artist's talent, there is now a mural showing two people in freefall holding a banner with our company's name on it. The clouds in the background trail off down onto the doors, where they draw your attention to the company name painted there as well.
I realize this isn't a cheap way to go, but it definitely gets noticed!
One other effective marketing strategy, no matter what style of lettering you choose, is to keep your truck clean. I know it feels like a losing battle in the winter months, but it works!