The boilerpipe library provides algorithms to detect and remove the surplus "clutter" (boilerplate, templates) around the main textual content of a web page.
The library already provides specific strategies for common tasks (for example: news article extraction) and may also be easily extended for individual problem settings.
Extracting content is very fast (milliseconds), just needs the input document (no global or site-level information required) and is usually quite accurate.
Boilerpipe is a Java library written by Christian Kohlschütter. It is released under the Apache License 2.0.
The real boilerpipe repository is available on google code at http://code.google.com/p/boilerpipe/. This is just my copy of the code base which I'm using to understand how it's been designed.