Headquarters: Mountain View, CA, USA
2010 Revenue ($ millions): 29,321
Rank: 4

What makes it so great?

Though Google has grown tremendously since its startup days -- the company hired 31.9% more employees this year than last -- the behemoth Internet company still operates like one in many ways, says an employee. "The amount of direct exposure we get to leadership and the fact that the well-being of employees is held in such high regard [are both] incredible."

With initiatives like 20% time (engineers are encouraged to spend 20% of their time brainstorming and developing new Google-related content, even if it never materializes), Googlers retain the innovative spirit that often gets lost as small companies grow into larger ones.

The company also provides mentoring programs for its workers: In Google to Googler (g2g) classes, employees train each other on technology, business, and personal interests and in gWhiz, any Google employee globally can register to answer questions or provide mentorship on an area of expertise.

Last updated October 28 2011: 4:50 PM ET