My sanity as a librarian in two separate buildings is assured when I use notes and lists. Memo and bulletin boards have an established reputation as conveyors of information. Imagaine my delight in reading a recent post on Larry Ferlazzo's Websites of the Day where he became of aware of a web 2.0 application called PinDax. At this site the user designs boards where messages can be posted much as one would do with pins and paper. A description of the board can be created along with a "look and feel" selection. Privacy and users can be controlled. As well as creating boards groups can be generated so users will be notified whenever someone in their group posts a note. Files can be attached to notes. Polls can be made. I liked the feature of looking at the most popular boards and newest boards to get ideas about usage in the classrooom.
At the same time Larry mentioned another site called Wallwisher. Depending on your needs this may be a better site for you to use. You can select a theme for your board, who can view and post to your board and the user can approve posts before they are seen. You simply double click to add a message, image, audio or video link. The advantage of Wallwisher is that the entire post can be seen when the board is accessed as opposed to PinDax where the message must be enlarged.
Both of the sites give the user the option of sharing the messages through a large variety of network venues.