There are 2 repositories under windows-shell-extension topic.
ShellAnything is a C++ open-source software which allow one to easily customize and add new options to *Windows Explorer* context menu. Define specific actions when a user right-click on a file or a directory.
A shell-extension (property sheet) that shows info about .NET assemblies on the file properties.
a windows shell extension for providing useful file tools
A Windows extension that is used to open applications quickly through context menu.
A Windows extension that is used to copy file(s)'s path through context menu.
A Windows shell extension to copy file names and paths
SharpShell makes it easy to create Windows Shell Extensions using the .NET Framework.