This is an excellent site that contains a multi-disciplinary approach to world history. Any subject area can benefit from this powerful, free resource.
EdutopiaEdutopia has great information about all aspects of teaching and learning. This is one of my top go-to resources.
National Geographic Educationa good place to start your research
English HandbookEverything you ever wanted to know about English grammar but were afraid to ask...
Purdue Online Writing Workshop...everything you ever wanted to know about writing for class, but were afraid to ask...
Project GutenbergFree literature...that's right...I said FREE.
Words without Bordersinternational writing site
VisuWordsa graphical dictionary & thesaurus