Apple Distinguished Educators (ADEs) provide reviews of educational apps for iOS devices.
IEducation Apps Review: http://www.iear.org
This community site provides reviews, news, research, and tutorials for i-devices.
Follow Richard Bryne's blog about Android-based apps.
This "mom" site started out to provide families with information, and then it expanded to educators as well, with tabs for iPhone, iPad and Android apps.
Bloomin' Apps (Kathy Schrock's Guide to Everything): http://www.schrockguide.net/bloomin-apps.html
Schrock strikes again with a plethora pf ideas for app use in school. She organizes them using Bloom's Taxonomy.
Bridging Apps: http://bridgingapps.org
This site focuses on apps for those with special needs.
Edudemic Best Educational Apps: http://apps.edudemic.com/
Search this site by age group, platform, cost and subject. It includes a Buying Guide.
The 40 Best iPad Apps for Young Learners: http://classroomtalk.com/?p=839
Fun Educational Apps: http://www.funeducationalapps.com
Arranged by age and subject, this was a family site that now includes information for teachers and schools.
Mind Leap: Educational apps for Children: http://www.mindleaptech.com
Mind Leap uses a 5 -star rating system (check out their rubric) for i-devices (and a few Android apps) from early childhood through middle school years.
Teachers with Apps: http://teacherswithapps.com
Started by two teachers, this site has an elementary focus and covers i-devices.