See this
article, which discusses the value of voting (in that case, in presidential elections, but the argument can be adapted more widely).
Specifically the above article responds to the commonly held view among a certain subset of economists (specifically, they're responding to a Freakonomics article, but I have heard the argument made numerous times) that voting is largely pointless. Because the articles are based on US presidential elections the structure pushes the discussion a bit further away from voting being worthwhile than it is here, but many of the points both sides are attemtping to make would still apply if they were arguing about the Australian electorate.
The rough gist is this: the original view is your vote has a vanishingly small chance of making a difference, so the economic benefit to you is too small for your vote to have a direct benefit to yourself. The opposing view is that you don't vote only for your direct benefit. If you vote strategically for the good of society (i.e. you try to help everyone, where "help" is whatever you think is the right thing to do for them), your vote actually does seem to be worthwhile.
If you're voting for whichever guy is offering you the biggest space at the trough, you're almost certainly wasting your time, economically speaking. If you're voting for a better society, the return on the investment of voting is worthwhile.
Now it turns out that in the Australian context the analysis doesn't quite carry over - we have to be there to get our name crossed off anyway, so the marginal cost of actually voting is effectively zero. And the differences in our voting system and parliament give our votes (relatively speaking) much more value.
But the principle is still a good one - your vote is much more valuable if you use it to support the principles you think are right, rather than if your vote is swayed by the promise of another $5 per week tax cut.
So vote, but vote for a good reason.
[That site, by the way, is a statistics blog. But if you're interested in politics, particularly US politics, you will find that they regularly post interesting stuff. The biggest news is probably that the sort of analysis you regelarly see in the media is generally completely wrong, and you should trust political pundits less far than you can kick them. And that you should probably kick them a lot.]