I found out a couple weeks ago when talking to one of the school board candidates online that you don't have to vote for all 8 (or however many you guys have to chose), you can vote for just 3 or 4 or none at all, if you want. Since I don't have (and likely never will have) kids in the school system, I'm just going to leave the school trustee section blank. (Since only 10 people are running for it, it's more like "chose the two people you don't want" than "chose the 8 people you do".) In the last election I just voted for women, since I figured women would be more interested in the well being of children than men.
Also, in Manitoba, Ontario and Alberta during provincial elections you can decline the ballot (hand it back to the election officer at the poll and say you decline your vote). Thunder Bay allows this municipally as well, so I am sure Winnipeg does too. These votes are counted as a "none of the above" option. Personally, I think voting should be mandatory and vote declining should be well known or a none of the above option should be on the ballot. Statistically, this is more effective than simply spoiling your ballot or voting for a minor candidate since it actually registers as someone being opposed to all candidates.