John, there was a post a couple of years ago of "Pictures of Your Bike with a Percent Grade Sign". It took about two years before I finally got to one of those signs. There are a few hills around here that have the "Steep Hill" sign (otherwise known as the "truck on cheese" sign), but you just won't see that percent grade on a sign around here. And the original poster is in Beaumont, which is flat as a pancake.

Teachme, a couple of other comments. Some of these electronic gizmos show the slope directly, so it's not like people run around measuring rise over run all the time. If you're interested in slope of a bridge, try photographing it from the side, then measuring on the photograph. You can also take a 2' level along, and measure from one end down and divide it out. And if there's 4 different ways to measure the slope of a hill, you're allowed to use whichever one sounds steeper. So on Church Hill, with my 2' level, I couldn't find a place on it anywhere that was over 5%, but the local cyclists are still convinced it's 7-8%.