Earlier quoted context omitted.
I've been thinking about this. Saying "I'm a software developer" just doesn't communicate what I do, even though programming is... well, what I do. Thanks for reframing the problem succinctly. You thought about this, so how do you describe your profession?
patio11's answers are cute, but if you say things like that you'll probably just end up defending yourself against people's misinterpretations. "So you're a teacher?" or "You mean like a security guard?" I think the best approach is a middle ground, rather than say what you are, or what the ultimate result is, just say what you _do_. "I build websites" or "I build iphone applications" or "I run servers and networks"…
You need to internalize something about marketing. When Patrick says, "I helped 2 million kids learn how to read", he has framed the conversation in terms of the value proposition he wants to talk about.
Statistically speaking, "nobody" cares about websites and iPhone applications. Moreover, virtually nobody --- even practitioners --- can tell the difference between someone who is good at building a website and someone who is working from a copy of "learn PHP in 3 hours". Saying what you "do" is a remarkably bad strategy.
If the thought of explaining the broad value you choose to provide to people produces cold sweats, my recommendation is "practice more".