Whenever you're working with a lot of smaller images you're supposed to combine them into a single one called a sprite. You can get an example of what I'm talking about by looking at Google's sprite, which has most of the little icons you'll come across while searching.

In our WrapUp earlier this morning we talked about how a new build of Office 2010 Beta had been leaked, and in this build Microsoft included new icons for each of the applications. It didn't take long for someone to extract all of the icons from the release and assemble them into an icon pack, which is exactly what one DeviantArt user did (our download mirror).