I am a big fan of pet projects; by which I mean hobby code that I have developed and continually re-develop in order to learn new and newer versions of developer technology.
I have done this in the past with a Windows wallpaper changer taskbar app and a piano scale and chord finder utility. These have gone through various VB, Delphi and C# versions. Each time the familiarity with the 'requirements' means that I can use them as a comfortable 'problem-space' in which to try to utilise new features and rework code.
I am just about to start a new pet project - this time to sort code (initially C#) in code files according to configurable rules. I've always wanted a utility that would allow me to organise/group code in order of construct type (e.g. properties, ENUM, methods etc.) or access (private, protected, public etc.), taking account of regions and respecting comments and areas like namespace containment of imports (using statements) and allowing alphabetic sorting within these groupings.
Eventually I hope to make this an add-in to Visual Studio that will help me to organise my code in place and at the same time master the dark art of VS automation...so CodeTidy is born.