Q: What's with the funky letters in "Østgarðr"?

A: The penultimate letter, which should show up as a curly d with a slash across its stem, is an "eth", an Old Norse (and Old English, BTW) letter corresponding approximately to the two-letter combination "th" in modern English. (Which also corresponds roughly to a different Old English letter, the "thorn" -- but let's leave that discussion for another time.)

According to Sunniva Saksvik, who's not in the SCA but lives in Norway and has studied Old Norse, the O with a slash through it is a modern Norwegian letter which did not exist in Old Norse. In other words, the word "Østgarðr" could never have existed in the Norse language: by the time "Ø" came into being, "ð" was already obsolete. The correct Old Norse spelling would be "Austgarðr".

Not that anyone's likely to change the name now. Indeed, somebody twenty five years ago objected that the name "wasn't correct Old Norse", to which the response was "who said it was supposed to be Old Norse?"