I'm just playing around with this web 2.0 app and it is pretty cool.
www.wallwisher.com
Quick to set up and the interface is easy to use. You can send out the 'wall' as a link and have students post ideas, words, etc. on the wall without having to login or open an account. As an adminstrator of a 'wall' you can select the option to have all posts approved by you first. The wall itself can be made public or only visible to you. You can also embed it or follow it via an RSS feed.
A great little tool - it will be interesting to see how teachers can use this in the classroom.
Here is one that I have started...
My wall on Differentiated Instruction
