Being a graphics ninja, Samuel's first example is on how to (finally) put widgets on OpenGL viewport. This is now made possible thanks to Qt 4.4's new feature of adding widgets to the graphics scene. Check out his example code, it looks awesome and you can play with it for hours!
Since I'm new to all this magical graphics world, my first example is however fairly simple: Bloom effect (with pure Qt of course). If you are an avid gamer, you know what I am talking about here. And just for the fun of it, I coded it so that you can drag-and-drop an image right from the web browser, e.g. Blooming your favorite Flickr photo easily.
Feedback is warmly welcomed. Enjoy!