Syllable is a small operating system that's easy to understand and enjoyable to program for.
Here is some software that I've written for Syllable.

• Transferrer - a GUI FTP client for transferring files to/from FTP servers. Includes contributions from other Project of the Month participants.
• VirtualDisk - a driver and command-line utility for mounting MS Virtual PC virtual hard disk (.VHD files) in Syllable. It has full read-write support, but currently only for fixed-size disks. Perhaps I will implement support for dynamically-expanding disks at a later date. VMWare virtual disk support is another possibility for the future.
• An example 'Hello world' GUI app - with lots of explanatory comments. Uses a StringView to display "Hello world" in a window. Get the source file here.

Some other things that I've worked on but aren't finished yet (email me if you're interested in any of these):

• A theme system, allowing visual theming of libsyllable gui elements by third-party plugins.
  Status: the API is more-or-less finalised, and a few libsyllable classes have been adapted to use the theme system. Some documentation has been written.
• A storage volume server, which manages mounting and unmounting of disks, removable drives, network shares, etc.
  Status: a prototype is done. Work needs to be done to properly integrate it into the system.
• A video driver optimised for Virtual PC.
  Status: working, but without any acceleration. Thus, it's currently no better than the existing VESA driver.