Here is a set of resources for scraping the web with the help of Python. The best solution seems to be Mechanize plus Beautiful Soup.
See also :
- ClientTable (see also this comment)
- Pull parser
- wwwsearch ‘s FAQ
- Simon Willison’s weblog on this topic
- Dive Into Python’s tutorial on HTML processing
Off-topic : proxomitron looks like a nice (python-friendly ?) filtering proxy.