Mission

The Goal, Purpose, Vision; Context; Meaning Of Life

it's extra-cool when you feel not just "we have a mission", but "we're on a mission" - Passion!

Shared Vision

Mission Statement - WikiWikiWeb:MissionStatement

Shared Language

Pascal Finette suggests: Eight words or less. Verb - Target - Outcome.

Guy Kawasaki says your Start Up need a Mantra, not a Mission Statement.

Martin Cagan prefers a Manifesto.