For my project CXRATE – Currency Exchange Rates in Ukraine I have made small fork of World Flags Sprite CSS and added there support for world currencies (USD, CHF, CAD, GBP, etc).
So now you can use flags when you output currencies like:
<ul class="f16"> <li class="flag usd">USA</li> <li class="flag cad">Canada</li> <li class="flag uah">Ukraine</li> ... </ul>
https://github.com/alexfilatov/world-flags-sprite
Currently only 16px flags added, will add 32px later.