Here are some of my FAVORITE chapter books for second grade!
Junie B. Jones by Barbara Park http://www.randomhouse.com/kids/junieb/
Judy Moody and Stink by Megan McDonald at http://www.judymoody.com/
Magic Tree House by Mary Pope-Osbourne http://www.randomhouse.com/kids/magictreehouse/books.html
Geronimo Stilton by Elisabetta Dami http://www.geronimostilton.com
Ivy and Bean by Annie Barrows http://www.anniebarrows.com/ivyandbean/