Lino It (13+, no-filtering, elementary, middle, high, parent-permission-required-under 13)
Lino It is a free sticky & canvas service that requires nothing but a Web browser. This sticky board allows users to post documents, websites, and photos. Use Lino It to create a classroom discussion board. Here is what their site has to say, “Access lino from your home, office, or even on the road and post a sticky note online whenever you need!…Attach your files to stickies and share them…”
Account must be created to use.
Sample of sticky board: