Beautiful Soup is an HTML/XML parser for Python that can turn even invalid markup into a parse tree. It provides simple, idiomatic ways of navigating, searching, and modifying the parse tree.

Here’s some code demonstrating how to extract data from HTML tables using Beautiful Soup.

version 4.0 of the venerable Python HTML scraping library is vastly improved -- it uses lxml as the backed for speed and has a significantly cleaned-up Pythonic API

A HTML DOM parser written in PHP5+ let you manipulate HTML in a very easy way!

ScraperWiki is a centralized location for these custom built scrapers. Instead of writing your own from scratch, you can search their database to see if a scraper has already been written for a source.

ScraperWiki lets you write your scraper in Python, PHP or Ruby, schedule scrapes and download scraped data in CSV format, as an SQLite3 database or via the API. You can fork existing scrapers too, Github-style.

point and click CSS selectors / generate appropriate CSS selectors for scraping particular content