With the iPad reaching three million units, it's no wonder that every computer maker wants to get in on the paper. Over the past couple months, we've seen a number of different tablets announced looking to add their own twist on the market that Steve Jobs has currently got on lock. Most recently, we've seen BlackBerry announce its tablet computer, the PlayBook. But which of these are actually going to make any kind of impact? We picked out six of our favorite tablets currently gunning for iPad's throne.