Foursquare, probably the best-known dedicated location-based service, topped 10 million users this week, up 100 percent from December. The company handles about 3 million user check-ins daily. And while it has yet to turn a profit, it recently raised $20 million in funding at a valuation of $100 million. Meanwhile, the company announced a deal with American Express on Thursday to credit card holders for linking their cards with their Foursquare accounts. In a test deal earlier this year in Austin, Texas, users reportedly spent an average of 20 percent more at local businesses.

Here are some of the notable players in the location-based space, and what their services can do for your business.

1. Foursquare

The company provides incentives for users by offering daily "mayor" status for checking in frequently at a given location. The person with the highest check-ins becomes "mayor" of that venue, at least until being dethroned by another user. also offers badges, from "Newbie" to "Superstar", depending on usage. And now its Checkmate app checks you into locations automatically when it detects you've arrived.

Business Upside: The partnerships Foursquare has made with large brands provide an idea of the utility it provides businesses. As a small or medium sized business owner, you have the same access to the technology that's checking millions of users in to local businesses around the country. Simply set a deal -- such as giving a free coffee with the purchase of a pastry to customers who check in on Foursquare -- let your staff know, and get the word out. Those who use the service and redeem the deal may enjoy a feeling of exclusivity, and tell their friends.