Short, but funny: Sam Ruby's Survival guide to i18n

"OK, so we've established that you've got a tool that you want to ensure is internationalized. The first thing I want you to do is to copy the string

Iñtërnâtiônàlizætiøn

into your tool and observe what comes out the other side. If you have a weblogging tool, put it in the title, summary, content, and any other nook and cranny you can find. Comments too, if you have got them. Check every output that can be produced, including html and feeds.

If the output comes out intact, you've passed the first test, and can go on to part two, cleaning windows."