Hayley Barna and Katia Beauchamp didn’t go to Harvard Business School planning to start a business. “No, we can answer that definitively,” Ms. Beauchamp told Betabeat. But they had a good idea, crunched the numbers, wrote a business plan and found out they couldn’t stop. Birchbox, which generates leads for beauty brands via a website that delivers subscribers a customized box of beauty samples every month, launched in the fall with $1.4 million in seed funding from First Round Capital, Accel Partners, Lerer Ventures and angel investors including Gary Vaynerchuk and Sam Lessin of drop.io. They’re up to 32,000 paid subscribers and 50 brand partners, meaning the company is already generating at least $3.8 million in revenue a year, and growing fast (and inspiring knock-offs).

Birchbox’s deliberative co-founders are building a long-term business, but we’ll be surprised if it’s the last venture we hear of from either of them. “We only have eyes for Birchbox,” Ms. Beauchamp said when Betabeat asked if they thought they’d ever start another company. Angel investing, maybe? “We would love to be in that position some day. Until then, we can offer free and candid information to entrepreneurs who have questions--we don't have all of the answers, but we can share our perspective and experience,” Ms. Beauchamp said.