To combine all the above: Breakout boards often describe one of two things
- Adapters to convert either connectors or ICs to a convenient footprint. This includes ones that go from a fine-pitch LCD connector to 0.1" headers, and boards with hard-to-mount parts (tiny surface mount parts, BGA or QFN footprints) and a header or connector. They often include other components that are always needed or have to be close to the part (bypass caps, pullup resistors, crystals).
http://www.sparkfun.com/products/9614 and
http://www.sparkfun.com/products/9719 are examples of this type
- Modules that encapsulate functionality, like a complete MP3 decoder/audio amp or USB to serial interface, that can be used as part of a larger project.
http://www.sparkfun.com/products/10277 and
http://www.sparkfun.com/products/718 are examples of this type
/mike