I must say, I feel a bit better about the Best Coaching Blogs snafu.
Based on the comments, it seems the rules need to be clearer and the "vote down" option needs to be removed. Plus we need intelligent protocols for checking what's going on. Otherwise, the competition is too tempting for some and too demotivating for others.
I think maybe, just maybe, I've found the solution. After a Google search (gotta love Google), I found www.strutta.com, which has some very intelligent looking contest software. I enquired about their security system for ensuring fairness and here's the speedy reply that I got: