I've been deluged with people asking:
Is it possible to learn more about programming even outside PGSS?The answer is: Yes, of course!
Here are some possibilities...
A lot of high schools and most colleges have programming courses, and they make an obvious next step. After PGSS, you'd probably find a programming course a bit slow. But it would also be more thorough. I think this is a terrific option, especially for beginners.
But you don't have to take a class to learn more. You can try it out at home. Using Java at home requires that you find a compiler to use in place of Metroworks CodeWarrior. I don't know whether you can get any of these at cheap prices.
JavaScript makes a nice alternative. JavaScript is a language for incorporating programs into Web pages. You can do some serious stuff with it. It has several similarities to Java, but it's a little easier. The advantage of learning JavaScript is that you can use Netscape Navigator or Internet Explorer to create your programs, by creating Web pages like you learned to do at PGSS.
The other nice aspect of JavaScript is that you can make neat pages to post on the Web. In fact, I just learned JavaScript last weekend, so I'm anxious to show off myself: There's my Hangman Web page and my Recursion Web page featuring a Towers of Hanoi program. And I'll go ahead and throw in a plug for Doug Ensley's Discrete Math page too. :-)
I've collected some links that can help you learn and use JavaScript.
JavaScript for the Total Non-Programmer
JavaScript Tutorial for Programmers
HotSyte (an index of JavaScript information)
Netscape's JavaScript Guide
Netscape's JavaScript Reference
And then there are those physical, printed things you can buy from the bookstore. Personally, I got JavaScript for Dummies, which is a pretty reasonable book. (The others I've seen are thicker and more expensive than appropriate.)
If you feel pretty confident about your programming abilities, consider high school competitions. I want to mention one particularly: the USA Computing Olympiad. Technically, this is a competition to represent the US at an international high-school-student programming contest; but trying to qualify for the team is just a secondary reason for competing: the tests themselves are fun. (I have to mention USACO since my brother Hal Burch is something of a coach for the US team.)
ThinkQuest is a very different competition. It involves working with a team to develop an educational Web site about anything. This doesn't necessarily involve programming or computer science, but it could.
I don't know about other relevant competitions, but I know they're out there.