The official name for collectible antique/vintage Gasoline Station items is "Petroliana". I don't have much of it, because its a popular area for collectors, and thus most of the interesting stuff gets really expensive.
I do have a couple of Gas Station related items, though. My favorite is an old Gilbarco Gas Pump that I found in Arkansas. She was a rusty mess when I got her, and heavy as all get out:
She still had the pumping mechanism inside, which is why she was so heavy. After getting her home, I was able to pull all that stuff out and get rid of it. Made the pump much easier to move around.
Here she is in my study, after I fixed her up:
And here she is all lit up: