Have you checked out Rafflecopter yet? If you host giveaways on your blog, you MUST check it out. It makes giveaways sooo easy. You set it up with a few parameters and it keeps track of everyone who enters. It also picks a winner for you at random. I'm using it for my current giveaway here.
Rafflecopter is having a launch party and to celebrate, you can win an ipad 2 or Kindle Fire. Read all about how to enter on the Rafflecopter blog here.