Some of my favorite Web 2.0 Sites
I tried to keep this list manageable for a classroom teacher.  They are listed in no particular order other than requiring or not requiring an account.                                                                                                                                  Last update: 3/16/2015

Sites not requiring an account:


Sticky note web page
en.linoit
wallwisher (now called Padlet)
   
Collaborative typing

Collaborative whiteboard

Collaborative chat site

Virtual Tutoring / Classroom
Know Lounge (Added 5/6/17)

Collaborative drawing

Private Twitter-like site


Transfer big files
wetransfer (<2GB)
transferbigfiles (100MB for free)
transfer.pcloud (Up to 5GB files) (Added 3/20/16)
DropItToMe (Added 5/13/16)

Word cloud generating
Jason Davies (Added 12/28/15)
Wordclouds (Added 8/23/16)
Tagul (Added 8/24/16)

Fun presentation tool
PechaFlickr.net (Added 7/20/16)

Online polling with mobile devices
Tally (Added 11/30/15)

Text to speech

IVONA (250 character limit) (Added 3/20/16)
FromTextToSpeech (Added 3/20/16)

Speech to Text
dictation.io (Added 3/2/16)
TalkTyper (Added 3/20/16)

Online timer
teachit 
    
Online timer/Random Picker/Plus
Name Picker Ninja (Added 10/2016)
   
Fantastic online simulations

Find copyright free items
    
URL Shorteners

File Conversion Sites

Online Printables
        Printable Calendars         
        Calendar Labs (Added 3/15)
        Print a Calendar (Added 3/15)
        Free printable posters
        Recite
        Quozio
        QuotesCover
        Printable Paper (added 11/16/15)

Screen Sharing    
Rhyme Writing
Free Clip Art

MindMapping/Brainstorming

Online Live Stats

Internet Live Stats (Added 9/30/15)

QR Code Stuff

Math Stuff
Eyeballing (Added 11/16/15)
SolveMe Puzzles (Added 8/27/16)


YouTube Viewing / Downloading
Watchkin (Added 3/22/15)
KeepVid (Added 9/28/15)
Or, use this neat trick: In the url, change "watch" to "watch_popup"  Example:
http://www.youtube.com/watch?v=wX78iKhInsc

Online Audio Messages
RecordMP3Online  (Added 3/15)
Vocaroo (Added 3/15)
Online Voice Recorder (Added 12/29/15)

Teleprompter
        Cueprompter (Added 11/30/15)

Noise Level Monitors 
Bouncy Balls  (Added 5/29/17)

Paper Writing Checker

Online Dictionary/Thesaurus

Free Animations

For the Music Lovers
Chrome Music Lab (Added 3/14/16)

Make Poster Size Prints
The Raster...(Added 11/16/15)

Music
Bensound (Added 9/15)
hatnotes (Added 12/17/15)

Free Images
       
Ookaboo
Photos For Class  (New, a favorite)
Copyright Friendly (Added 3/15)
Free Large Pictures (Added 10/15)
Disney Clip Art (Added 4/18/16)
compfight (Added 7/20/16)

Online Teleprompter
        EasyPrompter (added 12/29/15)

Gigapixel Pictures
        Gigapan (added 11/16/15)
        A gigapixel sample (added 3/5/16)

Learning / Review Games
Jeopardy App (Added 8/15)

Create Custom Maps
Create Custom Charts
PieColor (Added 1/5/16)
ChartGo (Added 1/5/16)
Online Chart Tool (Added 1/5/16)

Special keyboard characters

Online Typing Tools/Training
Fliptext (Added 11/16/15)

Writing Prompt

Free Stock Video Footage (Great for Green Screen) 
Makerbook.net (Added 3/18/16)

Art
Build Your Wild Self (Added 5/9/16)
WeaveSilk (Added 8/13/16)
        SmartyPins (Added 3/9/15)

Video Conferencing
Appear.in (Added 12/4/15)


Add Text To Pictures
PicFont (Added 8/21/16)
AddText (Added 8/21/16)

Cool mapping tool
geoGreeting! (Added 10/27/16)

Fill Your Screen with Word


Sites requiring an account:


Sticky note web page

Create your own poster/presentation
canva
    
Presentation and document sharing
   
Collaborative Publishing

Event Scheduling
   
File syncing between computers
Use this link to sign up and I get extra storage

Make pdf's flipable
youblisher
Here is a sample for you to see

Lots of fun things to do to your photos

Create slideshows (ask for education account)
   
Learning Management System

Online comic creation

   
Online, collaborative bookmaking

Online Testing/Quizzing
         InfuseLearning
         
Socrative

Screen Capture/Recording Tools

   
Texting Tools
Kikutext (This one allows for parent reply. Nice)
Cel.ly

Free Images

Free Stock Video (Great for Green Screen) 
        
xstockvideo
        videvo

Collaborative Drawing Plus Much More
        Scribblar

Online Video Editing