Of all the different social media tools I’ve tried (e.g. Twitter, Facebook, blogging, etc.), a new one I just started using, Foursquare, probably has the most potential for cause marketers.

Why?

Because the backbone of Foursquare is the businesses at which its members visit, check-in and score points.

When you pop into a store, bar or restaurant you can earn points, badges or can even become mayor of your favorite hangout if you “check in” enough. You can also share tips and comments with your friends, check to see if any are close by, give them a shout-out via text or phone and broadcast your Foursquare activities on Facebook and Twitter.

Smart businesses recognize that Foursquare lets customers build the buzz for them. Customers spread the news of cool hangouts or great places to shop, flag meet-up spots for friends, visit new places for points and revisit favorites to retain their title of mayor.

And businesses are working with Foursquare to reward members with everything from special discounts to free products.

As one article points out: “For businesses, it’s social media meets customer loyalty in a tangible and measurable way.”

And since cause marketing is all about helping businesses support their favorite causes in ways that enhances customer loyalty and favorability, Foursquare could be a great fit with cause marketing in a lot of different ways. Both in how Foursquare currently works and how it might work with future updates.

Here’s how.

1. A fellow Boston-based nonprofit colleague @gradontripp–and top ten finisher on Foursquare’s Leaderboard last week (201 points to my measly 68)–tweeted the easiest way nonprofits and businesses could work together.

2. I could use Foursquare this month to promote both Halloween Town and its presenting sponsor, iParty. With almost 50 stores in New England, we could offer the Foursquare mayor of each store on October 23–the day before the event opens–4 free tickets to Halloween Town. iParty would be thrilled because you become mayor by having the most check-ins at a particular business.

3. You all know that I’m a big fan of pin-up programs. Foursquare may be a good way of reminding and motivating consumers to support these lucrative programs. For example, this past summer my nonprofit did a pinup program with four New England businesses: Tedeschi Food Shops, Ocean State Job Lots, iParty and The Upper Crust. The program went well and we raised well over $100,000.

But what if Foursquare members were reminded when they checked-in to any one of these stores about the cause promotion–and maybe even got a discount when they supported it. This could help us raise more money at the register where cashiers are not always good about asking customers to donate.

It also helps the business to earn their halo by letting every foursquare member that patronizes that business know–in a way it’s hard for he or she to miss–that that business gives back to the community.

I also think you could offer a special discount to repeat shoppers at stores that sold pinups. Or maybe shoppers that checked-in at any three stores (say Tedeschi’s, Ocean State Job Lot, iParty) could be entered to win Red Sox tickets.

4. To support the above program, Foursquare could add a “Do-Gooder” badge for members to earn. And how about “Karma Points” for good deeds.

5. Foursquare could also be a useful for cause marketing percentage-of-sale programs like the Absolute Boston program I posted on recently. When you check-in at your favorite liquor store you could get a ping on Absolut Boston and its support for the Charles River Conservancy. Maybe Absolut or the store could throw in a 10% discount on a second purchase as an added bonus.

This would work great at Starbucks where Foursquare could remind members that five cents from every coffee sold goes to Product RED to fight AIDS in Africa.

6. I can’t wait for the Foursquare charity shopping event! A nonprofit could recruit businesses to offer generous shoppers a one-day discount when they show their Foursquare check-in. Imagine a bunch of Boston stores on Newbury Street hosting a weekend charity event. Donors/Shoppers donate $100 for discounts at some of Boston’s swankiest shops. When customers are ready to buy they flash their Foursquare check-in at the register, which confirms their discount, and then they move on to the next participating store.

The shopping fundraiser would be good for Foursquare too because shoppers would need to sign-up for the service to see all the great discounts right on their mobile device.

Foursquare is social media, but it’s also a game. And games are best played with others. Today’s game is how best to use Foursquare for cause marketing, and I think I deserve to be the mayor of this one. Sorry, Gradon.

But the games only begun and you can earn points in my book with your own ideas. You have the mayor’s ear.