Ya gotta keep ur eyes peeled for these things, TekSavvy is known for having these contests at certain times of the year. Usually your vectors are the TSI website, forum, DSLreports, Facebook & Twitter. Of course it helps to have someone like me to give a heads up when I see these events, I realize not everyone participates on FB or Twitter so usually I'll do a thread on any events I do see, just to keep my fellow DSLr's in the loop.
I must echo other people's setiments though that maybe TekSavvy might use our CID/OID's to draw from instead of the FB route, yanno like keep it in the fambly eh? I'd rather compete against the other 80,000 TSI customers rather than millions of professional FB-contestants who subscribe to hundreds of thousands of FB-based contests as a hobby. 
it takes some of the fairness and fun out of it all.
it takes some of the fairness and fun out of it all.