I used to think the same way until I moved to the UK and people expressed the opinion that YYYY-MM-DD is still an American format.

I guess because for them the day always comes before month.

Nevertheless, ISO 8601 is clearly the ideal format for its sortability and consistency, cultural imperialism be damned!

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.

Heh. At a previous job I advocated that format so much that people thought it was a Canadian format.

They were quite surprised when I told them the actual format that was used in Canada.