When the student surpasses the teacher
Today I saw a webpage designed and implemented by a friend of mine. He has gotten quite proficient with CSS, XML, PHP, and other web tools.
The funny thing is, as he reminded me, a couple of years ago, he didn't even know HTML. I gave a brown bag session in our lab where I taught the basics (linking, inserting an image), and he took that introduction and just ran with it.
Maybe now I can get him to teach me how to make that Flash map that lights up the particular state you cursor over :). But seriously, it's very gratifying; often you don't know what effect you have on others--but with Richard, I can remember when he didn't know what an HREF was, and now he's a better Web developer than I am.
I've had that experience with Ahror, too--I started teaching him Visual Basic, and he quickly became a much better programmer than I am. In fact, I have some news about Ahror, but it deserves its own post next.