As part of some downtime after our release of OnTime 2007 and the Axosoft Community Site, the developers here took a couple weeks to work on some other projects. As a learning exercise, myself and Adam, another developer here decided to write an RSS reader that would be single-source, and work on multiple platforms. Rather than stay with .Net and use Mono to work on the mac, we decided to use C++ as the language of choice.
This was my first foray into the world of unmanaged code, not to mention my first chance to work with an Apple computer for anything other than iTunes. We had to use several external libraries to accomplish this, they are listed below:
This was a very interesting learning experience for me (Adam, my cohort in this, has significantly more experience than I at unmanaged development). Coming from a .Net world, and never having to significantly worry about things like pointers or memory leaks to C++ really opened my eyes to a new programming style, and I think I've learned some concepts that I can apply in C# as well.
Screenshots:

Windows

Mac
The source code is here, so you can peruse through it if you dare. ;)