I second Kellie's recommendation of this book. It was really fun. It's probably aimed at kids aged 8 or 9 to 11 or 12. It's an easy read but good plot and good characters.
I also reread The Three Musketeers (Alexandre Dumas) recently, which I loved as a teenager, but now I thought it was kind of depressing. The plot gets pretty dark at the end. It's a good book, but I'm not sure I'll be reading it again.
And I reread The Hobbit, just for fun. I'm already looking forward to the boys getting old enough to read aloud with me because it's really a fun adventure, much lighter than The Lord of the Rings trilogy.