OK, this is pretty simple, but I thought I would post if (at the very least for my reference).
Problem: How do I make the Silverlight application the size of my browser?
Solution:

Add this line to the Page_Loaded event
BrowserHost.Resize += new EventHandler(BrowserHost_Resize);
Add this to the code behind file
void BrowserHost_Resize(object sender, EventArgs e)
{
Width = BrowserHost.ActualWidth;
Height = BrowserHost.ActualHeight;
}
(You may [...]