When the IBuySpy portal was released along with ASP.NET 1.0, I pretty much used it to teach myself programming with .NET. In January 2002, Cory Isakson convinced me that I should abandon the enhancements I'd made to it and join the Rainbow Portal project, even though this meant learning C# along the way.
More than a year later, I can't believe how Rainbow is growing. As I type this, I'm listening to the second hour of a broadcasted meeting between Cory and a handful of Boise, Idaho area developers using (or considering, I think) Rainbow for various reasons.
If you're new to .NET (or software development in general), Rainbow is an excellent place to start. The learning curve is steep (meaning “challenging, but short“), but the rewards are many.
It's exciting to be (even a small) part of a project that really has HUGE potential. Join Rainbow, and you are welcome to be a part of that, too!