Karl Shifflett's XAML Power Tools
If you're developing in WPF or Silverlight, or even thinking about doing it, here's a MUST HAVE download: Karl's XAML Power Toys are an incredible set of useful tools. My favorite? The tool that extracts the style from an existing control and converts it into (you guessed it) a style, so you can reuse it on other controls. Visual Studio 2010 has a similar feature, but as far as I can tell, works only on a single property. That's not much help! The XAML Power Toys includes far more, as well, and you can try the beta version for Visual Studio 2010, as well. These tools are highly recommended, and highly regarded out there in the wild. Go for it!