Backpack - make pages with to-do lists, notes, files, images, calendars, etc.

30 Boxes - online calendar

Nicenet - free tool to create class websites 

mynoteIT - student organizer, note-sharing, and more

Schoopy - classroom organizer, school website & educational games

Groupvine - group organizer, share documents, etc.

Thinkature - Real-time collaboration tool

Haiku - free LMS (Learning Management System)

Carmun - easy bibliography and research tools

Monkey On Your Back - harass your friends and loved ones with reminders to do stuff for you....

enGrade - online gradebook

Stikkit "Little Yellow Notes that Think"

Evernote - capture and sync a multitude of devices

Quizlet - online tool for creating flashcards and other study aides

Soshiku - Organize your high school and college assignments

School Rack -