...an admittedly weak argument.
Like many, I find the current FPTP electoral system a shambles. Its hard to find a reason to vote, when over 60% of the votes in a riding are tossed away as irrelevant after the winner has been declared.
After the failure of MMP in Ontario, I was embittered and swore that I would never vote provincially or federally again. Like many heated decisions, this one was rash.
Why I continue to vote (but am still bitter about the process).
1) It's the only game in town, (other than protest or rebellion). When you're dying of dehydration, you'll drink from the dirtiest water if its the only water available. Similarly, if you want to make your voice heard in our democratic society, you're only option is to vote. (Updater: As Adam points out in the comments, I contradict my original statement in point 2 below)
2) As one embittered co-worker describes the system; our government is run by big business and special interest groups. While I'm not THAT cynical myself, there is a point there. If you do not vote, you give more power to the funded special interest groups. As citizens, we do hold way if we speak in a collective voice. We got Elizabeth May into the debates by protesting her exclusion. We also let the powers that be know, (if only by proxy) the issues we support by the party we vote for. Granted if enough people skip the ballot box, then this power of the collective is lost. But don't let that dissuade you. Change only comes from action. Inaction leads to apathy and decay.
3) Lastly, your vote does mean something even if it doesn't change the balance of power in parliament. Parties are funded for an election based on their popular vote tallies. By voting for the party of YOUR choice, you help that party survive to fight another day. (And this is also why voting strategically may backfire. You may be denying funding to the party of your choice, and funding the party you find slightly distasteful).
I know there are arguments that can counter these above. If you are cynical and angry or totally apathetic, this won't change your mind. However, if like me, you still wish to be part of the process, hopefully these points will encourage you to get out and vote.
PS. It may not be an incentive, but the advance polls are a perfect opportunity to vote. I myself used them this weekend. Small to no line-ups, and the times allow you to vote at your convenience. You don't have to rush home the night of election and fight the crowds to register your vote. Its a very pleasant experience.