This site is written largely in Trebuchet, but most of the world is written largely in Helvetica. If you are a big fan of the typeface, there is a new film just out - Helvetica - which looks at how Helvetica conquered the world, 50 years after it was born. This is how the filmmakers describe the documentary:
"The film is an exploration of urban spaces in major cities and the type that inhabits them, and a fluid discussion with renowned designers about their work, the creative process, and the choices and aesthetics behind their use of type. 'Helvetica' encompasses the worlds of design, advertising, psychology, and communication, and invites us to take a second look at the thousands of words we see every day."
Helvetica the typeface was developed by Max Miedinger with Eduard Hoffmann in 1957 for the Haas Type Foundry in Münchenstein, Switzerland.