The word i18n is shorthand for internationalization. I deal with i18n issues every day at work, so I like to make sure that the programs I write work properly in this regard.
Sam Ruby’s i18n Survival Guide uses a very nice test string:
Iñtërnâtiônàlizætiøn
some i18n test cases using Iñtërnâtiônàlizætiøn
- with BBCode: Iñtërnâtiônàlizætiøn
- with Markdown: Iñtërnâtiônàlizætiøn
- as a wiki link: Iñtërnâtiônàlizætiøn
- as a fancy wiki link: Internationalization (this should link to the same page as above)
(If I attempt to create a new article called “Iñtërnâtiônàlizætiøn” by typing its URL directly into my browser, then Iñtërnâtiônàlizætiøn doesn’t display correctly. But if I use one of the above wiki links, then it does. Huh.)