Zocdoc, the health appointment scheduling startup that launched at TechCrunch 40, has announced that Marc Benioff and Jeff Bezos – two of Silicon Valley’s most prominent figures – have joined the $3 million Series A funding round it raised last month that was led by Khosla Ventures.

ZocDoc allows users to book their doctor appointments online, even for same-day appointments. The site is especially useful for urgent visits and procrastinators who may wait until the last minute for an eye exam or prescription refill. Doctors can also maximize the number of patients they see by using the system to help reschedule missed appointments or fill in last-second cancellations.

Since launching last September, ZocDoc has seen a 2,000% increase in the number of available appointments on the site, largely because of its base of doctors and patients expands by around 50% every month. Unfortunately the site is still limited by region, with support for Brooklyn and New York City. Given the healthcare industry’s resistance to change this is understandable, but if ZocDoc doesn’t expand to fill this need soon, someone else will.