This is one that really ticks me off. Websites offering wallpapers both widescreen (16:9 ratio) and standard (4:3 ratio) will sometimes pull a fast one with the widescreen versions. What they do is (for example) say you have 1280x768 as your resolution; they'll use a cropped version of the 1280x1024 version rather then a version of the 1024x768 that shoes a bit more at the sides. So, instead of seeing more, you're actually seeing less.

I've also heard of video games doing this for the widescreen resolutions.

Has anyone else encountered this problem? In my opinion, it's an awfully cheap and misleading tactic.