I saw this recently so I thought I would pass it on.
I love the 'rounded corners' feature. (see http://www.mochikit.com/examples/rounded_corners/index.html)
The round corners code is based on the Rico library ( see http://openrico.org/rico/home.page )
.. which in turn based its implementation on "Nifty Corners: rounded corners without images " see http://pro.html.it/esempio/nifty/