You could always point out a Skelly Gas Sign. Its the only one with a huge white "S" in the middle of a blue diamond and, of course, it had "SKELLY" written in the middle. Skelly Oil Company was founded in 1919 by Bill Skelly. Skelly Gas stations were huge in the 1960's but slowly declined after then. Skelly Oil was bought out by Getty Oil in 1977, which in turned into Texaco.
Skelly Gas Signs are very rare to find because a lot of them were wasted away or destroyed. You may be able to find reproductions but even they are hard to come by. There are chances that you could run across other types of Skelly products, so if you are lucky and get your hands on a Skelly Gas Sign, you should keep it.