Foursquare, about to celebrate its third birthday, is big but not huge. It has signed up 15 million users, hired over 100 employees and now boasts several million check-ins per day. That is impressive work for three years, but it must keep growing.

To do so, Foursquare co-founder and CEO Dennis Crowley says the company is in the process of redesigning its mobile app for a broader audience, disassembling it and trying to put its features back together in a way that's more useful and interesting. It has also launched new features on its Web site, such as the neat and powerful "Explore" tool, which can help you find cool places to visit in your neighborhood or in an entirely new city.

As Twitter realized a few years ago, Crowley says Foursquare is seeing a big chunk of its growth from people who want to use parts of Foursquare, but not necessarily broadcast to the world. That means building a service that's useful to more casual users, and not just early Foursquare diehards.

I recently sat down with Crowley at the company's brand new, roomy headquarters in New York City, for an idea of what's next. Here's a lightly edited transcript of our chat.

ReadWriteWeb: Where is Foursquare right now?

Dennis Crowley: I think we're starting to get to the point where people are starting to see where the product is going and where the vision is going. The most exciting stuff for me to watch is all these people who have been Foursquare users for a year or so, writing their own blog posts and tweeting their own stuff about "oh, now I get it."

After we launched Explore on the Web, they're like, "This isn't about points and badges anymore. This is about using the data that Foursquare's getting from check-ins in order to do all this interesting stuff about surfacing things that are nearby, things that I might like, places I should go, experiences that I should have." That's been our goal all along.

One of the big tasks that we have this year is getting people to think of the product more as something that's all about discovery and introducing them to new places, and making their experience in new cities and unfamiliar neighborhoods easier for them. As opposed to just checking in to unlock points and badges. I think we're still stuck with a little bit of that stereotype, and this year's about us getting out of that.

Foursquare's new Web-based "Explore" feature.

How do you get past that stereotype and grow?

The challenge isn't really that dissimilar than some of the growing pains and hazing that Twitter went through. For a long time, Twitter was "oh, it's just people tweeting what they had for lunch, or that they're going to the movies." That wasn't interesting for a lot of people.

Then they hit a moment that was a little bit of critical mass and a little bit of clarity, where people started using it to break news and share headlines and spread information. And that's when it started clicking for a lot of people. For me, I was always interested in it, but when the plane landed in the Hudson and that's how you were learning stuff faster than CNN was breaking it, or when Michael Jackson died, those were the big moments that I think solidified Twitter's importance for a lot of people.

For us, we're starting to get to that point where people see that we're more than just a standard check-in app. You can go into Foursquare any time of the day and it will recommend interesting things that are nearby. So it's not analogous - it's not exactly the same as the Twitter experience. But we have that problem of perception that we're still working to overcome.

I look at what those guys went through, and if you just keep pushing at the vision long enough, it will eventually turn itself around or make itself clear to people. That's why, looking at those blog posts, it's really rewarding for me, because I can see that the change is already happening already.

What will you change?

There's still a lot of work that needs to be done in the app. We're in the process of going through a redesign in the app, in a sense. We're basically taking all the stuff we built over the last two years or so, disassembling it... You put all the pieces on the table, and figure out, "Okay, what is the best way to put these pieces back together so that it tells the story of Foursquare in the way that we want it to be told?" And I think if we can do that properly, then that's our ticket to really being able to effectively communicate how powerful the data is and how powerful a lot of the tools are.

A peek at Foursquare's brand-new, sunny headquarters in New York

What about making money? Will we start to see more advertising-based content in streams?

It's a project for the near term. That's a lot of what the Amex stuff is. (Foursquare has a broad partnership with American Express.) It's experimenting with merchants to figure out a way that we can put products that are monetizable into the Foursquare product, in a way that you don't look at it and say, "I can't believe Foursquare put advertising in the stream." You say, "this is great, there's a $10 discount here."

Since 2009, we've been pushing different ways to get merchants involved in the conversation with users. If users are looking for places to go, put merchants in there to help entice them. We did it initially with mayor specials, we're starting to do it now with the Amex stuff, and we'll be continuing to push that.

Our belief has always been, in order to connect people to places, and places to people, there's a way to insert a dialogue with a merchant that in a way doesn't feel like advertising, because the users are getting some tangible benefit out of it. It can be just special treatment, like you get to cut the line. It could be that you save a couple bucks. It could be that when you bring your friends, you get something special. There's a whole wide variety of it. It's just rewarding the user for things that they'd be doing anyway with Foursquare.

This is a bit out-there, but Netflix has built up a huge advantage for its streaming movie service by getting it installed everywhere, from new TVs to videogame systems. Can you use that concept for Foursquare, in a car perhaps?

Yeah, why not? I think anywhere where you see maps. Any map should have Foursquare dots on them. The dots could be representative of a number of things. It could be where your friends are right now. Or once you put your car in park, these are the five things you should be doing in this neighborhood.

And you could see a world where it's like, here's five things that I'm looking at, and I instantly send them to my phone, and then as I'm walking around, Radar (a serendipity-manufacturing Foursquare feature) buzzes me to let me know about them. When you think of all the other places that you'd probably encounter maps, being able to put Foursquare dots on them is a really interesting thing for us.