Coding in .NET for about 2 years, I got hooked up with the framework damn!
I am not gonna talk about cross platform challenges that Java guy raised. I will do it another day. But hell, what kind of application you want to build? It remind me of an old expression from Microsoft "Where do you wan to go today?" :)
How about creating a ticket system allow user to plug their webcam and capture image do a quick selection (face of cause) and then add it to card tray send cards direct to printer.
How many day? lines of code? will you need to write in C/C++.
At the end of the day, I am the on who scratch my head trying to get thing to work it such a great experience. I hope that my client would enjoy using it ;)