According to The New York Post, Foursquare ranks third in mobile apps–behind only Facebook and Twitter. The NY-based startup founded by Dennis Crowley has more than 10.4 million unique monthly visitors, according to a Nielsen report. That’s a 118% increase from last year. Pinterest was the fastest-growing social network, with a 1,000% increase in online visitors over the last year. Facebook led all social networks, both online and mobile. But Google+ is on the rise. Its app ranked forth on the list, with 9.7 million mobile users.