Poll everywhere is a great way for teachers to quickly survey their students (whether for learning, a pop quiz, or a fun intermission from the lesson is up to the teacher). They do this survey via cell phone.
This website is a great tutorial website for high school English students as they can do this without my assistance unless there is a troubleshooting issue.
ReadWriteWeb is a great online resource for both educators and students alike as it is rife with online information which makes it accessible from virtually anywhere.
This allows students to place sticky notes anywhere on the web. So when we are reading texts online or when they are researching online, they can place these sticky notes anywhere with their comments.