... in the page title, and in the body: äöüßÄÖÜ

Other accents too:áéíóú

[RS] adds all of the iso8859-1 characters above 160, for even heavier testing:
 160:  ¡¢£¤¥¦§¨©ª«¬��®¯
 176: °±²³´µ¶·¸¹º»¼½¾¿
 192: ÀÁ����ÄÅÆÇÈÉÊËÌÍÎÏ
 208: ÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞß
 224: àáâãäåæçèéêëìíîï
 240: ðñòóôõö÷øùúûüýþÿ

[KBK] edits the page to see whether the characters get damaged in the round trip.

[mjk] I can promise, that in this Wiki will visit some browsers, that will convert ISO-8859-1 characters to UTF-8. You can find my little rant from my user information page. Unfortunately, I'm yet unable to identify, which browsers change character encoding (I have tested with Mozilla 1.6, Firefox 0.8 and IE 6.0).

Let's test links: [testing umlauts: äöüßÄÖÜ]... Moo!