Warriors by Erin Hunter c:
Yayyyy, warrior kitties! This book series also got me into roleplaying, heh. Actually, in grade school a bunch of my friends and well.. really.. my whole grade read the series. So at recess, we'd go out into the feild and divide ourselves up into 'clans' and pretend to be cats. I miss grade school.

Oh, and the Magic Tree House series. I remember doing a few book reports with these books.