Chris Woodyard

USA TODAY

Sure, you've probably never heard of National Coffee Day.

But it's here, and several major chains are offering free cups of Joe, discounts or a chance to do some good.

The best deal appears to be coming from Krispy Kreme, which is offering a free cup of coffee and glazed doughnut to anyone who shows up. Starbucks is taking a different route, using the occasion to boost its campaign to donate coffee trees to Latin American growers who have lost crops due to fungus.

It isn't just coffee chains that have been roped into this holiday (of sorts) — truck stops, convenience stores, doughnut chains and others are getting in on the act. Here's a roundup:

• Dunkin' Donuts. The chain, with 12,000 locations worldwide, plans to use the occasion to celebrate its 66th birthday. Dunkin' Donuts says it will be selling medium cups of coffee for 66 cents.

Its also says it is going to "surprise" 66 of its Twitter followers with gift cards good for a year's worth of free coffee.

• Krispy Kreme Doughnuts. No purchase is necessary for anyone who wants to get in on the free deal. Just visit a store to get a free cup of coffee and a free glazed doughnut.

“We have decided to sweeten the deal a bit for National Coffee Day, as we think coffee and doughnuts go better together,” said Jackie Woodward, chief marketing officer of Krispy Kreme Doughnuts in a statement. “Our doughnuts have always been complemented perfectly by our coffee, and we are excited our guests are able to enjoy both of these premium products for free.”

No purchase is necessary.

• Pilot Flying J. The gas station and truck stop chain will give a free small cup of coffee — or another hot beverage, such as tea or cappuccino — to those who can show the online coupon available from the company’s Facebook page.

"We believe that we have the best coffee on the interstate," says Ken Parent, president of Pilot Flying J.

• Starbucks. The nation's most prominent coffee chain isn't offering a discount, but it is hoping customers step up to help save the planet — or at least the coffee industry in a distressed region of Mexico.

Starbucks will donate a coffee tree for every cup of brewed Mexico Chiapas cup of coffee in the U.S. or Mexico. The promotion has already been underway for those who buy bags of coffee, but extending it to cups for a day should help its goal of reaching 20 million trees by year's end. It's going to support the fight against a fungus called "coffee rust," which is destroying trees in Latin America.

Starbucks says it has donated 10 million rust-resistant trees so far and has the funds for another 8 million.

"The initial distribution of these coffee trees has already had a positive impact with potential to help farmers and their families for years to come,” said Craig Russell, executive vice president of Starbucks Global Coffee, in a statement.

• Tim Hortons. No free coffee but a social media contest. The #TimsCoffeeDay social media contest will take place on Twitter, among other places.

• Le Pain Quotidien. The Belgian cafe and bakery chain is offering half off any size of coffee