searchebay.py is a small Python script I hacked together that performs searches on eBay, analyzes the results, extracts individual listings, and builds an RSS feed from all the data. This RSS feed can then be used in, for example, MacReporter to monitor eBay auctions without having to constantly search eBay yourself. I find it practical.
The usage is very simple: python searchebay.py +contax +zeiss -ikon -o=contax
would for example search for Contax and Zeiss, filter out all Ikon items, and primarily find Contax lenses by Zeiss.
The result is saved in contax.xml in the public_html subdirectory of the active user's home directory (~/public_html/contax.xml). On Windows, you need to set a HOME environment variable that points to a directory with a public_html subdirectory.
Then run the whole thing regularly on a web server via Crontab or Scheduler and create a corresponding plugin in MacReporter (MacReporter Forge is sufficient for this). Of course, you can also use other RSS-capable news aggregators.