That's frustrating. One of the tacks I've taken is to point out that if they don't vote, they don't get to gripe about the outcome and that if you don't participate in democracy you can't expect to be a part of one. That at least tends to make the people I'm around feel guilty for not voting.
And really, it's kind of amazing to find young people in Seattle who don't vote. I mean, the Stranger makes it stupid easy.