Here's the steps on sharing your iphone application
1. Use your computer’s iTunes account to buy whatever iPhone application you want (we’re going to use Super Monkey Ball for demonstration purposes)
2. Download the application to iTunes and sync to your iPhone or iPhone 3G
3. Get to your family member’s, or friend’s, computer and log in to their iTunes application with your credentials
4. Log out and back in
5. Find Super Monkey Ball and click “Buy”
6. Re-download Super Monkey Ball
7. Log out of your iTunes account
8. Log back in with your family member’s iTunes account
9. Sync the iPho
Tutorials on How can you share iphone apps
