What makes it so great?
Biotech leader has uncommonly loyal staffers. "Wild horses could not drag me away," says one employee. Last year 537 employees took a six-week paid sabbatical, which is available for every six years of service.
Headquarters: South San Francisco
Top 3 (of 9) U.S. locations: South San Francisco, CA, Vacaville, CA, Oceanside, CA
2005 revenue ($ millions): $6,633
Full list: 100 Best Companies to Work For