Something that I have always loved about the Mac interface is the way that a bit of text will actually shrink slightly in an attempt to fit in a confined space. It has been a feature since long before OS X, and if you are not looking for it, you might not notice it at all.
For example, open iPhoto or iTunes on a Mac. The left side of the window lists your groupings or categories, and you can grab the vertical bar separating the listing on the left from the rest of the window. Drag the bar slowly towards the text, and notice that the lines of text will shrink just a little bit before they concatenate themselves with some dots at the end. It is as if they are giving you a bit of wiggle room with the interface.