How do I style a select dropdown with only CSS

Question

Is it possible to style a choose> dropdown using simply CSS?

Without using any JavaScript, I need to style a select form as much as humanly can. What CSS attributes can I use to do this?

This code must work with all popular browsers:

I'm confident that JavaScript will work with Firefox, Safari, and Internet Explorer 6, 7, and 8.

And I'm not referring to basic styling. What can we achieve with CSS alone that is the best?