Google Docs:  http://docs.google.com

Create, collaborate, and share documents, spreadsheets, presentations, sketches, and forms. 

Google Apps for Education:  http://www.google.com/educators/p_apps.html

Special tools and environments for education - included Google Docs, and more.

Google Blog:  http://www.blogger.com

Use to create a blog for your class to collaborate and share ideas, information, etc.

     NOTE:  When used outside of the Google Apps for Education environment, all of the Google Docs and Blog have limited usefulness in the classroom, because they require students to have an email account for Google Account setup.  Google Apps for Education is a good product, but requires centralized setup and administration for a school or district.  (These are, however, great tools for collaborating with your colleagues and friends.)

Google Maps - http://maps.google.com

Not part of Google Apps suite - can be used without any registration or login.  Maps and satellite images of the world, from global viewpoints to street-level detail.   

PBWorks Wiki (like this one):  http://pbworks.com

Wiki for collecting, sharing, collaborating, and discussing information, projects, etc.

     Tutorial:  Using PBWorks to put class materials online.pdf

PBWorks Educator Community:  http://educators.pbworks.com/

Educators discussing how they use PBWorks, examples, tools, plugins, etc.

Screencast-o-Matic:  http://www.screencast-o-matic.com/ 

Create screencasts and upload them to a streaming video server or YouTube.

     Tutorial:  Using Screencast-o-Matic to Create Screencasts (also Jing).pdf

Glogster:  http://edu.glogster.com

Create, collaborate, and share colorful presentations within a private classroom environment.  Scroll down to see classroom examples that the teacher has made public.

    FAQ explaining Glogster educational environment: http://edu.glogster.com/faq/

bit.ly:  http://bit.ly

Shorten long web links, customize short links with your information, track number of visits to your links

Diigo:  http://diigo.com

Social bookmarks:  store your bookmarks on the internet, organize them with tags and lists, comment on them, share them, and discuss them with others.  See what other people have bookmarked.

ThinkQuest:  http://www.thinkquest.org/en/

ThinkQuest is a protected, online learning platform that enables teachers to integrate learning projects into their classroom curriculum and students to develop 21st century skills.  The service is free to K-12 schools.  It offers a library of learning projects, project competitions, and an environment where teachers and students can collaborate.

TeacherTube:  http://www.teachertube.com/   

"Safe" site for videos (maybe your school won't block this one).  Can upload and download video clips from this site, just like YouTube.

Vimeo:  http://vimeo.com/

Upload screencasts or videos to a streaming video host site; free and paid versions.

ePals Global Community:  http://www.epals.com/  

Free email - closed community, no email in or outside the ePals community.  Email can be translated into other languages, facilitating global communications.  Other services cost money.