A while back I wrote a post for Download Squad on getting free stuff by entering contests on blogs. Here's the thing, while major media contests usually get thousands of millions of entrants, smaller blogs often get dozens, or hundreds.
If you use Google Blog Search, you can sometimes find blogs with very low readerships that are giving stuff away. Be the second person to leave a comment on the entry, and you could walk away with a mildly valuable prize. It's a win win for everybody, because these contests can help drive some traffic to those blogs, while entrants have a chance to win something. If they lose, they may have been turned on to a new site.
Of course, when you're talking about bigger blogs like Engadget, your odds of winning are starting to approach lottery territory, as thousands of people regularly enter these contests. I'm not saying you shouldn't enter, I'm just saying you shouldn't hold your breath.
And then there's the mid-sized blog. Uneasy Silence does a pretty good job of keeping track of technology news. Today they're launching a contest to give away a Nintendo Wii. All you have to do is post a link to the contest somewhere on the web. That could mean saving it to a social bookmarking website, or writing a review on your blog (much like this one).
In the last 8 hours, it looks like forty+ people have entered, and the contest runs through April 6th. So I'm not saying your odds of winning are good. But hey, it's a free Wii.