The euro symbol is in UTF8 (e2 82 ac), but it's not one we're likely to use (though I never know!)
I did try an iconv from window-1252 to utf8, as some of the test data was showing up as that encoding in the database. However, the iconv failed with an "illegal input sequence" error, which prompted me to check the database dump, whereupon I discovered that the "illegal" character sequence been dumped as UTF8! It seems that mysqldump had converted it on output. As a result, I didn't bother with an iconv conversion from ISO Latin 1.
I think that some of the users compose their text in MS Word and paste it into the browser to create their posts (the board is for roleplaying so lots of long story fragments) so the encoding of some of the text might be different to the board encoding. I haven't verified this theory yet.
I'm still checking the board and testing character sequences and encoding, but so far, I've been able to paste in Ogham, Greek, Cyrillic and Old German, so it works for new posts. I'm still going through a sample of pre-existing posts to see if any have encoding errors.
