In addition to real estate, you can invest in other real or "hard" assets like gold, silver, oil, and jewels. Although these assets do well in inflationary times like the 1970s, over the long run these assets will only keep even with inflation, and you need real growth above the rate of inflation if you want to get ahead.
So before you put money into rental real estate or gold, I'd recommend that you make the maximum contributions to your tax deductible retirement accounts.