As you dig deeper with Silverlight 2 you will start to want to customise some of the built in controls. Now a nice way to start working with a new style I've found in WPF land is begin with the default template in place and then tweak from there. Now in WPF this is really easy to do with Blend but in SL 2 it's currently a little more involved by either reflectoring the Silverlight Controls dll and examining the generic.xaml resource or by accessing the styles on MSDN here.

However a neat alternative is a very cool WPF tool over at Delay's blog that gives you access to these templates - handy stuff!!