Most of these sites are free but may offer more services via paid subscription.

Edmodo - A wonderful free site that creates an educational environment for students that focuses on skills such as blogging and collaboration.
Dabbleboard- A collaboration application--a whiteboard
Diigo - An ideal site for social bookmarking that allows teachers to create student account for sharing and annotating links.
Doink- create animations
Kidblog - One of the top ways for students to create blogs in a safe environment.
Kippt- allows you to quickly save web pages while browsing until later.
National Jukebox- makes historical sound recordings available to the public free of charge
Quizlet - study vocabulary or almost anything ;create your own flashcards
Polleverywhere - create real-time survey experiences at events using a mobile device.
Screenr - Create instant screen casts
Skrbl - Multi user whiteboard
Shapecollage- free automatic photo collage maker; make picture collages in less than a minute with just a few mouse clicks
Studyblue - create study flashcards online.
SymbalooEdu - A great visual way for teachers to share sites and resources with students.
TinyURL- type a lengthy URL in the text field and create a tiny URL that will not break in email postings and never expires.
WallWisher -- create a"wall" to post messages.
Wordle- generates "word clouds"
Zunal - A fantastic webquest creator for teachers.
Fakebook - makes Fake facebook pages

Game Creation

Jeopardy Labs --allows you to create a customized jeopardy template without PowerPoint. The games you make can be played online from anywhere in the world. -great games that teach all types of skills - for students to create their own learning games

Helpful Sites

Easy Bib - A free automatic bibliography and citation maker
Learning guides - Lively Learning Guides by Experts & Educators

Super Book of Web Tools for Teachers -- great website to find thousand of web 2.0 tools

Mind Mapping Tools (Graphic Organizers) -- free online, easy to use with students,mind mapping application.
Gliffy - free online mind-mapping application.

Webspiration Classroom - From the creators of Inspiration, a wonderful graphic organizer that now allows for online collaboration. One of the best visual outline creators on the web.
Quicklyst - A free user friendly site for creating outlines. Quicklist also integrates with a search engine and dictionary for enhanced note taking. Study queues can be made as well.
Knowcase - Create collaborative outlines with this easy-to-use site that features a drag-n-drop interface.
Thinklinkr - A real-time collaborative outline creator that has a nice built-in chat feature to engage in project development.
Checkvist - A great collaborative online outliner that has an abundance of features such as: gmail/browser integration, mobility, and nice import/export features.
CRLS Outline Maker - Takes users through a step-by-step process to create an outline.
Read Write & Think Outline Maker - A very easy-to-use outline creator that teaches how to create outlines.
Loose Stitch - A nice fun site for creating collaborative outlines that can the be exported to a blog or website.
Wisemapping - More of a mindmapper than pure outline creator, but still a great visual site that teaches the basic concepts of creating an outline.
Mindmeister - A fun site for real-time collaboration that is ideal for creating brainstorms, mind maps, and outlines.

Timeline CreatorsMnemograph - free timeline builder
TimeToast- create and share timelines on the web
Xtimeline - Create, share and discuss interesting timelines.

Wiki Enhancers