I always met at Think and never really thought of it as a startup place, just one that is convenient. But now that you mention it I do run into all the startup folks there now. Good stuff, though they stopped serving lemonade :(
I personally use Foursquare for nothing more than tracking my travels. Initially, I checked into places just so that I could go back and look at my Foursquare history to remember where I was and when I was there.
Then I realized that I should be archiving that data off-site and plotting it on a map for my readers to see. So I wrote a Python script (i.e., hacked together a Python script) that reads my Foursquare history KML feed every 30 minutes and then appends the data to a master KML file on my web server. I then use a plugin called jKMLMap to show my travels on a Google map on my site: http://raamdev.com/travels/#map
I think Foursquare has (had?) huge potential. The digital and the physical world are coming together and apps like Foursquare allow us to connect the two. The trick, as is the trick for any startup, is to figure out how you can monetize such a bridge. I thought the idea of allowing businesses to give away coupons for checking in or becoming the mayor was a great idea, but that's subject to abuse and I'm not sure how that makes Foursquare any money.
If Foursquare improved on features that allowed businesses to incentivize using Foursquare, and made such incentives worthwhile to patrons as well as businesses (product reviews, service reviews, maybe a way for patrons to offer suggestions to business owners for improving business, etc.), then I think Foursquare could save themselves, maybe by charging businesses for offering such features once there's a demand for them by users.
News about Foursquare has been pretty bleak lately. I tried using it to find restaurants but their search results page was a disaster on mobile: tiny text and it wouldn't allow zooming in. They just updated the Android app but it has a bunch of reviews along the lines of "doesn't work": https://play.google.com/store/apps/details?id=com.joelapenna... All this when they apparently have only 20M users, which seems low for how long they've been around.
Any HNers with an optimistic view, and/or use Foursquare and think it's awesome?
I use Foursquare whenever I travel. I find it especially useful when I am in a new airport. I can usually get information of the best security lines, best places to eat, where outlets and wifi are, etc.
If you read HN then you understand the benefit of reading users comments after you read an article. Foursquare lets you read users comments while you are visiting a location.
However I am not sure if/how this translates to profitability so I am not speaking to that end.
I use it fairly religiously and love it. I like the nearby updates for adhoc meetings with friends and - because close friends of mine also use it - it provides a nice way to estimate full party arrival. And it has a lot of Amex $5 off deals. I've probably saved $100 on those. I also use it to find nearby pubs and such when in unfamiliar cities.
And, of course, I still like earning new badges.
edit for additional note:
If you have friends that use it heavily while on tours it is fun to track their travels. Follow an entire band or tv crew on tour and get anecdotes from different personalities live updated as they travel - it's like a real reality show in small doses.
If you like the savings from check ins, have a look at our connected app, GeoPerks (http://4sq.com/Q8uIW3). You get replies to checkins at venues where you have membership discounts and rewards (e.g. AAA, museum memberships, student discounts, etc.).
Funny, I re-started using it again last year after ignoring it for several years.
I've noticed I get lots of little freebies when I check in via foursquare. Ie., $5-$10 off a meal if i use my amex, a free dessert etc. Lots of local businesses seem to have these hidden deals but they don't publicise them.
Once (a couple years ago) I'd see foursquare stickers and offers of discounts for checking in and people would use it, but I don't know any of those 20M anymore - within my world (SF, SOMA) foursquare seems to have dropped off the map.
All the news and data seems to show that Foursquare peaked some time ago. Naveen one of the founders left; several pivots (remember that a pivot is done when things are not working out); well known employees leaving (Morgan Missen, Tristan Walker, and now Naveen's partner); declining use of the app; down round; etc. This company is now burning Series D cash raised on November, I guess there is no more fun and games here.
It is sort of mind boggling that revs are so low with 150 employees, and having been around as long as they have. They should definitely be able to make sizable coin through partnerships with retailers offering deals or discounts when their customers announce their presence in a retail location via a check-in. This seems like a lay-up for both four square and retailers. Why are they not doing more biz in this arena? Retailers pay to track customers in the on-line world, why can't foursquare grab money for tracking them in the offline world? Are their structural impediments?
Foursquare is integrated into a lot of other products. For example Instagram and Path both use Foursquare to get nearby locations when uploading an image, and I'm sure there are numerous other services that do the same thing. There is still a tremendous amount of API usage even if it doesn't seem like such a huge "buzzword" app from a direct user point of view.