Great Apps!

http://www.appolicious.com/curated-apps/1043-4th-grade-app-pack-recommended-downloads

Apps for education
http://www.apple.com/education/apps/

Top 50 apps
http://www.appstoreapps.com/top-50-free-education-apps/

Best math apps
http://www.brighthub.com/education/k-12/articles/63422.aspx

10 best Apps for Education
http://www.brighthub.com/mobile/iphone/articles/65863.aspx

60 great apps
http://60apps.wikispaces.com/