[cwilbur]

I agree with this list - completely in spirit, though I'd probably recommend different languages in a few places - but I'd also recommend at least playing with a couple of "industry-standard" programming languages.

Playing with C++, for instance, especially after having used C and Java, will give you a better understanding of what not to do. And if you play with Objective-C for a while too, you'll see two ways of handling object orientation that are dramatically different: what seems like a minor difference makes for drastically different expressiveness and flexibility.

I'd also recommend picking up Perl, for a different understanding of what not to do. Ruby is at its core a reimplementation of the good parts of Perl, with inspiration from Python and Lisp, and it hits a very sweet spot as a result; Perl has a lot of good parts, but it has a lot of warts that seemed like a good idea at the time and have been preserved for backwards compatibility.

And one of the things that I've noticed is that Real Programming focuses on interfaces in a way that toy programs don't: in web programming, for instance, you're more constrained by the browser-CGI-server interface than anything else. In programming for platforms with GUIs, the learning curve is not the language you use but the API to the window system.