After I completed my Topps baseball sets, I started chasing the baseball wax pack inserts (coins, rub-offs, stamps, etc) and it's become one of the favorite parts of my collection.
It appears I've done the same thing with my Topps football cards (down to ONE card '72 Topps #266) and I'm now chasing the wax pack inserts
1960 Topps Team Emblem Stickers, Topps first football insert set. 33 stickers for the full set, I've got 15 of them so far: