UPDATE, July 2011: I'm now using the WordPress-Amazon-Associate plugin, so much of what's written below is no longer relevant. WPAA seems to do almost everything in one easy-to-use plugin, so give it a go if you're interested.

Some time ago I started looking into ways to add Amazon products to help monetise a WordPress site. My major requirement was to automatically set my affiliate IDs for a range of different Amazon stores, with products appearing depending on a user's worldwide IP location.

I was working on a site with a potentially global reach (aren't they all?), and didn't want to limit the potential by pushing people towards just one Amazon store. Here's how I did it. Continue reading →