"Developers typically see a tenfold productivity increase when they switch to Python" according to Bruce Eckel, speaking during a Design Patterns In Python class.
Check out Bruce's Thinking in Java. I bought the printed version of this after going through the first couple of chapters of the soft version. Highly recommended.
Thinking in Python is an interesting project. It isn't a Python tutorial - it's mainly about patterns, with implementations in Python.
If I were interested in C#, I'd take a look at Thinking in C#, a preliminary version of which is now available. But I'm not, so I won't.
Peru is proposing a Free Software law. Check out Microsoft's FUD letter, and Congressman Edgar Villanueva Nuņez's superbly reasoned response.
See here for the originals, and links to coverage.
Have a go at Clifford Pickover's ESP Experiment. Works for me.
Does it work for you?
Update: It's been explained to me now. Clever! I won't spoil it for you, though.