There are so many posts on summer reading ideas, and I find myself responding to all with the suggestion to visit the section on award winning books (from the UK, Canada and Australia as well in addition to the big name US awards) on SmartBean :) The award winners are organized in excellent fashion.
The other books listed/recommended in the store (besides the award winning ones) are also great titles. You may get some ideas from their recommendations for the 9-12 and young adult age groups.
Incidentally the site recommends StarClimber - the third in the Kenneth Oppel trilogy that Nancy recommended - it recently won the Canadian Library award.
Shuchi, I've read the first Oppel Airborn out loud 3-4 times, it is great! The biggest hit of the year was The Hunger Games by Suzanne Collins. I read it outloud to my gifted 6th graders--they only come one day a week so we had to read it pretty fast. The last day of class I read for 2 hours--they were mesmerized, every time I tried to stop they rioted!! It's intense but really well written and great for tweens and teens. Watch for the movie!
Check out Cybils blog. It awards the best books every year in multiple categories--I get a lot of ideas from them.