I've noticed for a while that when I try to access to some FTP sites or media that contains files with special characters like á é ñ, etc (yes, I speak spanish), nautilus substitutes it by a ? character . When you try to copy it to a FAT or ISO filesystem it throws an error. Of course, this happens 'cause these filesystems don't support characters out of certain limits. Of course, it's all about character encoding, but I think that it would be nice to have some autodetection in that cases, just like konqueror does.

Regards
Mauricio