Lots of review and price comparison sites use contextual advertising. This is where a sites adverts adjust themselves based on page content. So if you have a page about the latest netbook or smart phone, the adverts there will should only display that kind of product.
I made a tool to help with contextual targeting for eBay Partner Network affiliates. Click on the screen shot above and take a look. For anyone who didnt know, eBay is split up into different geographic territories. Each has its own ID and list of categories (category tree). Also each uses that areas language: ebay.fr is in French, ebay.nl is in Dutch and so on!
I’ve collected ALL of this data and made it available as an Excel 2003 spreadsheet.
All non-english categories have a translation. Everything is updated every Friday.
More eBay tools from R.O.EYE: http://ebay.cgmlab.co.uk/
Contact me for help with the API call, Python code or other formats.