WordPress Post Thumbnails Revisited
Shortly after the release of WordPress 2.9, I published my technique for bulletproof post thumbnails. Since then, it's evolved yet simplified into a more robust solution, specifically for use in WordPress themes. The problem, was that each image uploaded was generating a new set of images in various sizes, on top of the three that WordPress creates by default. This resulted in 6 or 7 images, instead of just a handful. While this isn't really a huge deal, it means you're going to be using more space on your server, and the uploads directory will get a bit unruly.