I took an ordinary submit button and declared font-size (15), color (black) and decoration (bold) as well as a 5 pixel padding to give some space, and this is what these different browsers did with it:

Internet Explorer 6

Internet Explorer 7

Firefox 2

Opera for Macintosh

Safari

An old Mozilla

Camino

Groovy. 

The Mozilla browsers are the only ones that seem to adhere to all the declarations. The Explorers add a strange white space and some fairly arbitrary color choices to the mix (not to mention corners that bring tears to the eyes), while Camino adds a strange gradient and Safari just ignores everything and puts an Aqua bubble.  My favorite is the Opera button because it doesn’t add any drop shadows, but who wants to use Opera??