For something that I happen to be doing tonight, I needed to extract full-resolution pictures from Yahoo! Photos. They make that hard to do because I'm sure they're big fans of the revenue they get through their print services.

Turns out, though, that it's not impossible. They have a "Print at Home" feature, and if you load that little pop-up window and view source you'll find a couple image URLs embedded in the javascript. One of them, arrImgLandscape[0] (or perhaps arrImgPortrait[0] depending on what your picture looks like) has the full-res URL you're looking for.