At work I have recently been working on some system software that integrates closely with the registry. This means I require some fairly in-depth knowledge about the Registry APIs, and I also need a way to test their functionality (both with and without my software involved).
I have done this in the past by writing custom code, which then gets lost or out-of-date. This time around I decided to make a more interactive and reusable tool to help me accomplish this, and my company – FSLogix, Inc. – decided to release the tool as open source on CodePlex. I also wrote a blog article with more in-depth information about the tool over at the FSLogix Blog.