Mathews Genesis is a great youth bow as well because it's incredibly adjustable both length and poundage wise, so he won't grow out of it right away. I'm not sure if it's small enough for a 7 year old or not, but I would certainly suggest looking into it.

EDIT - They also have a Mini-Genesis that is available in 6-12 lbs. The Genesis is 10-20 lbs.

http://www.mathewsinc.com for more info.