There are lots of contest pages to look at for inspirations, but few do a good job of having all of the necessary elements that lead to a viral campaign.

Appsumo did a great job with this Macbook Air giveaway campaign, and although it's long done and gone, I've got some screenshots to share with you.

The URL was quite simple in order to get some good SEO juice as this campaign ran for a few month. It was www.appsumo.com/macbook

They kept the actual page and copy very minimalistic and focused on the prize (for you and a friend! This contest is already social, who wouldn't want to be the baller who helps his/her friend win a new Mac?)

This first page does a great job of drawing you in. There's only 1 call-to-action (CTA) and a big green button that commands your attention. They've also put the contest end date in plain sight and the official rules are available under the product image.

Now that you've answered the question on the main page it's time to enter your email. Simple enough. There was also a subtle change in the button copy and size which makes you feel like the site is friendlier and that you are a part of something after this step.

Finally, the last page makes it super easy (and very clear that the more of your friends that signup, the better your chances are to win).

Finally, they end it with a simple line of text that does a lot. "Which of your friends wants a MacBook Air the most?". This is done in a playful way, but tries to spark competition and cooperation in who can invite the most people into the contest in order to better their chances of winning.