http://www.mrfiddle.com
This site has Suzuki Book 1 in a midi format that you can play along with. Scales available here too.

http://www.violinandviola.co.uk/
Has some free sheet music downloads, scales, etc. on this site.

http://www.sheetmusicarchive.net/
Classical music downloadable free.

http://www.sheetmusicplus.com/
Great source for purchasing music. If teachers purchase 2 or more copies of the same piece, they receive a 15% discount. Free shipping when orders are over $25.

A selection of useful and fun musical games on the Internet:
http://www.metronimo.com/uk/index.htm
http://www.creatingmusic.com/
http://library.thinkquest.org/15413/games/games.htm
http://www.happynote.com/music/learn.html

Shar
http://www.sharmusic.com

Go Strings
http://www.gostrings.com

Southwest Strings
http://www.swstrings.com

Kindermusik
http://www.kindermusik.com

Music Together
http://www.musictogether.com

From the top
http://www.fromthetop.org

Strings magazine
http://www.stringsmagazine.com

The Strad magazine
http://www.thestrad.com