Xman, you're the man! I was disappointed the first time I went to fill my GTO at the gas station. Only to realize that there was no place to hang the cap whilst filling up. Just had to let that baby dangle down on the paint job.
I had thought about cutting or disconnecting the tether and doing it the old fashioned way - put the cap on the gas pump.
The method I use is a zip tie that wraps around the gas door hinge arm and captures the gas cap lanyard. When you get to the gas station, you simply slide the zip tie up the hinge arm, keeping the cap out of the way!