Padlet (formally Wallwisher)

Image linked from here

They give you a blank wall (think of it as a canvas) for FREE and then you put anything you want on it. Richard Byrne who writes the blog, Free Technology for Teachers, has a great article/video on how to create a Padlet Wall for Your Classroom. It seems very easy to use, just drag and drop the different components. Padlet has fun, flexible layouts, with many designs and backgrounds.

Everything auto saves and who doesn’t LOVE a program that auto saves? Padlet has instant collaboration, meaning that you can see everyone's activity on the wall instantly without reloading the page. And who doesn’t LOVE a program that refreshes a page automatically?

Padlet lets you to paste a link to a YouTube video, drag a word document from your computer, and take a picture from your iPad camera. You can also embed the wall on your blog or website. 

Padlet is educator-friendly. It allows you keep your wall private between students and classes. The creator of the wall decides who has permission to change what is written on the wall and who has access to see the wall. It is designed to be viewed on your phone or tablet as well as your computer, laptop or TV. 

Some competing brands include: PrimaryWall, "a web-based sticky note tool designed for schools that allows pupils and teachers to work together in real-time" and lino, "a free sticky and canvas service that requires nothing but a web browser."