Trading stamps, which almost all stores and gas stations gave out, one for every $.10 of your purchase. They were pasted into books, then the books traded for merchandise at special stores run by the stamp companies.
S&H Green Stamps were most popular, followed by Top Value, Plaid, and King Korn. My grandmother collected Green Stamps and every few years traded them in for toasters, irons, etc. To their credit, S&H at least kept the stores open long after retailers stopped giving stamps.
I also remember the filling stations giving out drinking glasses and place mats with a fill up. One each time, you had to keep coming back to collect the sets.
