The Countdown has begun. They’re flying off the digital shelves of Apple’s App Store for the iPhone and iPod Touch. Apple is closing in on a big milestone in the iTunes App Store: 1 Billion iPhone Apps downloaded.

There’s a very good case to be made that the iTunes App store is in terms of items downloaded, First, you have to be amazed that people have downloaded one billion applications for the iPhone and iPod Touch. iPhone sales themselves hit 17 million last month, so the app volume logically follows. Second, you can win some cool stuff if you download an app between now and the time that Apple reaches the one billion mark.

To enter the contest go to the App Store and download an app or you can click here to fill out the Alternative Entry Form.

According to the contest rules, you can enter up to 25 times per year. You are automatically entered to win a $10,000 iTunes Gift Card, an iPod touch, a Time Capsule and a MacBook Pro.

Additionally, Apple has posted the top 20 free and paid apps on the App store. The most popular free App is Facebook, followed by Google Earth, and Pandora. On the paid side the most popular app is Crash Bandicoot Nitro Kart 3D, followed by Koi Pond, and Enigmo. Games make up 15 of the top 20 paid apps, and 6 of the top 20 free apps.