I'm curious.
How many of the people who think voting is useless use Google, Wikipedia, del.icio.us, digg, YouTube, and so on?
Each of these websites, like the mechanism of the election itself, is a democratic process. Some of them are more similar to the election than others, but they are all aggregators of opinion, in one form or another. Aggregation, in these cases, is a mediator of trust. It's hard to trust a single stranger, but it's much easier to trust a million of them, because it's far less likely that they'll be wrong.
Disagree with the masses? Go and convince them. Ultimately, the American system is in fact run by the American public. It is entirely possible to do something about an opinion you don't like, by driving the public in the right direction. Of course, the actual mechanics of doing so are very difficult, but if you really do care about it, that shouldn't stop you.
And I think I need a separate post to rub Keith the wrong way again.