The iTunes App Store launched on July 10, 2008, and to celebrate the five-year anniversary, they're giving away five games and five apps for free.
Here is the iTunes Store page with download links for each.
Infinity Blade II
Superbrothers: Sword & Sworcery EP
Tiny Wings (Tiny Wings HD also free)
Where's My Water?
Barefoot World Atlas
Day One (Journal / Diary)
How to Cook Everything
Traktor DJ for iPhone (iPad version also free)
*UPDATE 07-09-2013* EA is joining in the fun!
Dead Space for iPad
The Sims Medieval
The Sims Medieval For iPad
Mirror's Edge for iPad
Flight Control HD
*For some reason, the reddit post doesn't include the Peggle games, but search for them - they're free too!