At our wedding I wanted all the decorations to coordinate. This included the signs.
I didn't want there to be some last minute black and white print out. This would be jarring and ruin the effect of all the other things we had designed (flowers, programs, table settings, etc.) So I bought a bunch of plain wooden frames at the dollar store along with some craft paint, and painted them up.
Here I am with my step mom as we painted all of the frames.
Then I created signs that used the same colors and visual elements from our wedding invitation and placed them in the frames.
We had one for the ceremony area, wedding parking, at the bar (I've written about how to make a wedding cocktail menu from an e.m.papers seating list here) and for the bathroom.
It was easy, I just printed everything with my little Canon color printer on to regular weight craft paper.