5. Linden Lab
First Address: 333 Linden St., San Francisco, CASecond Life was born on narrow Linden Alley in San Francisco's quaint Hayes Valley neighborhood. Founder Philip Rosedale worked in the warehouse with a single engineer. Three years later he moved to a larger office on, naturally, Second Street. Company headquarters are now in San Francisco's financial district, while the original space on Linden is occupied by a Moroccan furniture store.