Ok friends, I need your help.  What are your favorite kid's series'?  My kids are huge readers and they've pummeled through a lot of what we've got.  We're looking for something new.  
We've done:
Magic Tree House
Nancy Drew
Junie B.  (she's a bit sassy for my taste though)
Boxcar Children
American Girl
Encyclopedia Brown
and a few others that I'm forgetting at the moment.  
Shoot me your favorite so that i can stock up before we head back overseas.  They also LOVE biographies and have read almost all of the Historical and Christian Heroes put out by YWAM.  I highly recommend those, by the way.  
Thanks!