I am not a drinker, but this, per E.D. Kain, seems like an unappreciated accomplishment for the 39th president:

If you’re a fan of craft beer and microbreweries as opposed to say Bud Light or Coors, you should say a little thank you to Jimmy Carter. Carter could very well be the hero of International Beer Day.

To make a long story short, prohibition led to the dismantling of many small breweries around the nation. When prohibition was lifted, government tightly regulated the market, and small scale producers were essentially shut out of the beer market altogether. Regulations imposed at the time greatly benefited the large beer makers. In 1979, Carter deregulated the beer industry, opening back up to craft brewers. As the chart below illustrates, this had a really amazing effect on the beer industry:

Possibly this was all a plot to jack up peanut sales. But it worked.

It's worth noting that Carter got no political credit for this move, and that the benefits didn't appear until long after he departed. Some policy successes -- like a successful war or peace treaty -- yield immediate political dividends. But others produce little change until many years later, by which time everybody has forgotten your policy had anything to do with it.