The Smithsonian's kids website. Encyclopedia Smithsonian has a great variety of online activities and website for children of all ages. 

Awesome blog by a "cybrarian." Includes resources for up to 12th grade but also includes sections for ESL and New Teachers. Section on K-5 has a great list of valuable website for lower elementary teachers. 2013 Edublog winner for Best Library/Librarian Blog.

Graphite's list of the best summer apps for kids and their parents. Recs are based on teacher evaluations and rated by "learning rating" and "teacher rating." Geared toward lower elementary students.

Interesting and inspiring news website for educators. Focused mainly on K-12 but offers good insights into the overall U.S. education system from an educator's standpoint. Includes links to blogs and browsable by grade.

Interactive, (fairly) educational website aimed at preschool and elementary students. Includes online storybooks, online activities, printable worksheets and book recommendations. Topics include music, shapes, colors, animals, etc.

Great resource for teacher's with Latino students or want to provide an accurate "window" into some aspects of Latino culture.

New York Public Library's Kids website. Books lists, ebook resources, kid-friendly websites, parent and teacher resources.

Amazing children's bookstore in NYC. Great for teachers and students alike. Great website with book reviews, classroom ideas and videos. 

Easy recipes for Pre-K kids! Great ideas for actively involving children in the cooking process.