The Twitter Book $, by Tim O’Reilly & Sarah Milstein. A full-color guide to effective twittering for businesses and individuals. Includes lots of examples and advice.
Twitter Tips, Tricks, and Tweets $, by Paul McFedries. Step-by-step instructions and advice for smooth twittering.

Artículos y Sitios

The Boston Globe. Restaurants using Twitter for cheap, effective marketing.
New York Times. Mom-and-Pop Operators Turn to Social Media.

El API de Twitter

El acrónimo "API" significa "Application Programming Interface". En el caso de Twitter, proporcionamos un método de la API method para casi cualquier funcionalidad que se puede ver en nuestra página web. Los programadores usan la API de Twitter para hacer las aplicaciones, sitios web, los widgets, y otros proyectos que interactúan con Twitter, lo llamamos el ecosistema de Twitter.
Mashable. Tweetable eats, what street vendors can teach businesses about Twitter.
BusinessWeek. Why Jack & Suzy Welch are now big fans of Twitter. To those with eyebrows aloft, read on to find out how it happened
CNN Money. 5 Twitter tips for your company

Blog posts

Zappos Blog. How Twitter can make you a better (and happier) person from Tony Hsieh, CEO of
10 Twitter Tips for Nonprofit Organizations (but great advice for any business), by Heather Mansfield.