If you're being practical and are just trying to get a certain politician elected or ballot measure passed, then requesting that people vote within a demographic that is likely to vote in a predictable way (Democratic on HN, I'm sure) is duplicitous. You pretend you don't care what party people vote for, but anyone can tell that a "Rock the Vote" campaign on MTV is intended to get youth Democrat votes, or that bussing in impoverished people is intended to get Democrat votes. Never is the idea why people should vote actually explained, but that doesn't stop them from shaming those who don't. Republicans tend to be a little more frank as to who you should vote for and why.
Which is why I say, vote Meg Whitman, because the State of California is broke and she is more likely to contain the spending. Vote to legalize marijuana because it's high time people stopped being sent to jail for smoking pot. And if you're thinking of voting otherwise, I encourage you to stay home. Because a vote is not a moral obligation. It's a serious political act that changes the structure of society, and I would rather my preferred changes happen than that they be as democratic as possible.