Came across something interesting today – I went looking for an icon in SharePoint 2010’s ribbon, and came to a file called formatmap32x32.png. Interestingly, it contains:

So, it actually holds lots of icons, but the image is cropped using CSS at display time to only show one of those icons. Nice to be able to see a bunch of the icons in one place easily.

(Though not all buttons come from this file – other icons are ‘stand alone’)