I Bike MPLS sticker
I like this one. It's my most popular sticker.
Available to you, one buck per, plus postage.
Dimensions, you ask? Just under 3 inches by just over 2 inches (that's about 70mm by 54mm for you non-US-type persons - plus or minus a few mm, depending on how I'm feeling).
Have you seen one of these stuck someplace? Tell us where.