Teachnology
http://www.teach-nology.com/subjects/math/ (some free sample - membership required)

Smart Kiddies
http://www.smartkiddies.com.au/ (free access for teachers - membership required)
Year 1 to 7 resource

Analyze Maths
http://www.analyzemath.com/

iTute
http://www.itute.com/download-free-vce-maths-resources/

Tools for Understanding
http://www2.ups.edu/community/tofu/home.htm (excellent source of lesson plans and resources)