Harvard isn’t exactly known to be a community of slackers, but one recent Harvard graduate might have set the bar a little bit higher: he’s only 25, and when he’s not attending class at the Harvard Business School, he’s busy investing in 15 start-up companies.

Oh, and did we mention he already has a million-dollar start-up of his own?

Joshua Kushner ’08 started Vostu.com in his junior year along with Daniel E. Kafie ’05 and Mario T. Schlosser. Vostu, an online gaming site with a social-networking spin, now has 35 million registered users, 180 employees, and 15 million dollars in support from Intel and General Catalyst, according to a recent profile of Kushner in Business Insider.

Kushner’s past endeavors share a common theme: an interest in networking and social interaction in the Internet age. He founded the Friendship Circle of Boston, a non-profit that fosters friendships between students and children with mental disabilities. Unithrive, a service he co-founded, encourages Harvard alumni to act as mentors while providing zero-interest loans to students in need.

But according to Business Insider, Kushner’s new pet project is a much bigger one—he’s already invested in fifteen start-up companies, including GroupMe, Paperless Post, Hot Potato, and Sailthru. And he hasn’t stopped there: with a $10 million fund to spend on the latest, hottest start-ups, he’s hoping to expand his portfolio further into the field of online social media.