If your job or hobbies require you to do a lot of measuring, you might want to take a tip from this guy who had a ruler tattooed on his forearm.
"My right forearm has a 8" ruler on it that I use for everything from measuring PVC diameter to wire lengths," Flickr user, mikeysklar said. "My background is in embedded hardware design, but I choose to spend my time doing experimental building, transportation, and energy these days. The tattoo gets used daily."
Very interesting... if you value entertainment over practicality for body inking, check this out: