(and yeah- my first thought, and greatest motivator, is the complaining power you gain by voting! )
I hate this argument. Voting offers no change in rights... not intrinsic and not moral. The same day that this gains you the right to complain is the same day I get to blame voters for all the problems in government.
As far as the voting because one has children - I see this as a need to believe we have the ability to influence the future through an action. It doesn't speak as to if we actually influence the outcome.
That's why I said write a letter. Voting for someone is so statistically insignificant and the end result so unknown (read: voting "small government Bush" on that basis...?) that the time spent to vote is better spent somewhere else - even if you still wish to influence your governance.
Hence - the more local and the less actors, the more value one's vote and one's participation is.
You don't have to vote if you don't feel like it... all political canidates are just liars anyway... but having more intelligent voters would be a little chance more of never having another bush for president...
Let's say we are in a classroom and the teacher decides that the classroom should have new carpet. What color should the new carpet be? I don't know. Let's call a vote! Quickly you realize that even though you want green carpet, to vote for it would be just throwing your vote away, since everybody else seems to want red or blue. And then you think, "Wait, I don't care what color carpet we have. Am I voting for the color of carpet that I actually want more, or am I voting for the color of carpet that I think will please the most people?" Eventually, you decide to vote for the blue carpet, since all of it's supporters went around saying that red carpet is more likely to cause rug burn.
Out of 30 voters, 16 people have voted blue and 14 have voted red. Yay for the majority. Who cares if the majority got what they wanted, there's still a great number of people who are upset. You start to think, "Oh no, I am one of the bad people who voted for blue out of fear, and now everything is ruinned!" I didn't want to make so many people unhappy with my decision. I should have voted for green anyway...
And then teacher says, "Actually, we're just going to put down brown carpet. It was the cheapest and we already bought it 2 weeks ago. I did use all of the money I was allowed for new carpet though, by striking a deal with the carpet guy so that we both made profits for our slush funds."
I would say that if you have to ask that question, voting would probably be a waste of time for you. And if you actually want to do something, it's going to require a lot more than voting.