Participants of recent seminars offered by Brett Smith gave answers listed below with the most common appearing first.
What teaching material or supplement has been most helpful to you in your teaching in the last year?

1. Music K-8 Magazine
2. Music Express Magazine
3. Activate Music Magazine

Other Ideas shared:
Text or Series
Share the Music books & CD's 2
Spotlight on Music 2
Silver Burdett Music Connections Series
An American Methodology - great year-long sequence for each grade level
Technology
Wikipedia via Google
Ipod
Guitar tabs
Musictheory.net
Music Ace
Methods/Lessons
Orff Level I
Teaching Recorder
Boomwhackers
Dulcimer
Flashcards
DonMar Solutions - notation cards
Rockin' Rhythm Raps
Little Kids Rock!
Ed Sueta's Recorder Method book
Rhythm dice games
Singing Games
JW Pepper Editor's Choice Series
Networking with colleagues
Experiencing Choral Music Series