Diary of a Wimpy Kid by Jeff Kinney.
this one was the hands-down winner in the poll, but there are not multiple holds on titles
Dork Diaries by Rachel Renee Russell
lots of votes, plus there must be a new entry, because it made the multiple holds list in May
I also put this in the teen list--tons of holds on the upcoming Mark of Athena
Artemis Fowl by Eion Colfer
Also on the teen list. Perennial favorite, with new titles always coming.
Magic Treehouse by Mary Pope Osborne
Still on the list!
Bad Kitty by Nick Bruel
The only picture book series that made the list
Warriors and Seekers by Erin Hunter
These have cross-over appeal with teens, and are still popular!
Rainbow Magic by Daisy Meadows
Still on the list--mostly due to multiple holds