I saw some of these sprites long time ago on some spiegel.de subpage and from time to time I see smaller sprites within stuff I get from our HTML-team - but this article and it’s insights into realworld design, is really great … continue on Smashing Mag - The Mystery Of CSS Sprites
And that’s where you should start with it - as always AListApart is the best source for Web-Designers … AListApart about Sprites