It's no secret that football and basketball are the two most popular sports betting activities in the United States and that baseball ranks a distant third. But with baseball being pretty much the only game in town until the NFL preseason begins in August, sportsbooks are looking for ways to separate customers from their money and as a result have come up with a number of unusual betting opportunities.

Nathan's Famous Hot Dog Eating Contest

The first one is a bit of a mainstay in the sports betting world and that involves Nathan's Famous Hot Dog Eating Contest on July 4 in Coney Island, N.Y. Joey Chestnut has dominated the event in recent years and brings an eight-year winning streak to this year's event. He holds the record for eating 69 hot dogs in 2013 and ate 68 in 2012, but dropped off to just 61 last year, despite receiving a run for his money from Matt Stonie, who gobbled down 56 dogs in the contest.

With Chestnut dominating the event, sportsbooks may be a bit hesitant to place odds on the overall winner, although those will likely come out a day or two before the event. As of now, you can wager on whether Chestnut eats more than 65.5 hot dogs or fewer. The over is -130 and the under is -110.

Sotheby's Art Auction

Those who enjoy art will find a trio of offerings and the wagers will be graded by the final selling price at Sotheby's. You can wager whether the final selling price of  Francis Bacon's "Study For A Pope I" will be over or under 40 million pounds, whether Andy Warhol's Front And Back Dollar Bills" will go for more or less than 19.5 million pounds and if the final selling price of Jean-Michel Basquiat's "Orange Sports Figure" is more of less than 7.5 million pounds.

It's obvious that I am no art connoisseur, as I wouldn't hang any of the three on my walls if they were given to me, so from that perspective, I'd have to look at the unders.

Woman on $10 Bill

When U.S. Treasury Secretary Jack Lew said that there will be a woman featured on the new $10 bill in 2020 to mark the 100th anniversary of the Constitution's 19th Amendment, which gave women the right to vote, sportsbooks realized that there was a possible wager out there and have posted odds on most of the logical choices. By law, the person depicted on the bill cannot be alive, which rules out Oprah.

While there are odds posted 22 different women, it's hard to go much farther than the "Big Three" of Harriet Tubman, Rosa Parks or Elanor Roosevelt. Tubman is the favorite at 2-to-1, while Parks is second in the odds at 5-to-2 and Roosevelt is at 3-to-1 odds.

There's a big drop-off to the fourth choice, Helen Keller, at 10-to-1 odds.

Frances Perkins and Jane Addams are both 12-to-1 and Wilma Mankiller is 20-to-1.

Patsy Mink, Jeannette Rankin, Juliette Gordon Low, Clara Barton and Admiral Grace Hopper are each 25-to-1.

At 30-to-1 are Betsy Ross, Molly Pitcher, Alice Paul, Susan B. Anthony, Abigail Adams and Dr. Sally Ride.

The biggest longshots at 40-to-1 are Margaret Sanger, Emily Dickinson, Lucy Burns and Amelia Earhart.

When the organization Women on 20s made a pitch to have a woman replace Andrew Jackson on the $20 bill, Tubman was the winner of their poll, narrowly beating out Roosevelt. Surprisingly, Parks was a distant third. While I believe Tubman and Parks are both excellent choices, I'll have to give the nod to Tubman on this one.

Others

There are also the usual political wagers one can dabble in and as of June 25, Hillary Clinton and the Democrats are still good-sized favorites to win the presidential election in 2016.

There are also several Game of Thrones wagers, several movie propositions on opening weekend take, along with various bets on the price of gold at the end of the year and the relationship of the Canadian dollar compared to the U.S. dollar.

If you like to bet, the odds are pretty good that you can find something to help fill the idle summer months until the action on the gridiron resumes.