I dream (awake!) of The World seeing that date, thinking something along the lines of "but hey, that's annoying, I'm not sure which date that refers to!" and then just adopting ISO 8601 immediately.
For anything handwritten (cheques, dates on signatures etc.), I use YYYY-Mmm-DD (e.g. 2012-Jan-10), as I can't imagine anyone confusing the meaning of it. I avoid DD-MM-YYYY and MM-DD-YYYY, as I usually end up having to check what I meant. No one has commented on it yet.
Typed, I use YYYY-MM-DD (e.g. 2012-01-10), mainly for its sortability.
Well, in Poland we do use D.[M]M.[YY]YY too, which is unfortunately quite popular, as a short version of the format with verbal month "D MMMMM YYYY r." (r. stands for "rok[u]", i.e. year). This long version is predominantly used in lots of official forms and letters here.
YYYY-MM-DD HH:MM:SS.ffffff+ZZZZ