I recently discovered two really neet tools that helped me with Windows Store app development.
Windows Store Icon Maker
When creating a Windows Store or Windows 8 apps, there are many icon sizes you have to provide. If you do nont wat to do all the resizing by yourself, you can use the Windows Store Icon Maker. It is a fork of the Windows Phone Icons Maker with added support for Windows Store apps. It takes a 300x300px icon as input and outputs all the square icons you need.
To brand Windows Store apps written in XAML, you need to override all the control styles. This sucks if you just want to change the colours to match your theme. HAMMER.Pants solves this, by auto-modifying all the coloured brushes so you don’t have to pick through them. Currently, you provide a “base” colour, and HAMMER.Pants modifies that based on the luminance variation found in the original styles. That is, if you pick red, all the purples will be replaced with reds, but they’ll change in brightness slightly just like the default purples do.