"Pirate Pad is a Collaborative Word Processor. Everyone sees what the other writes. The document is then exported to one of the participants' computers for off-site sharing." This would be helpful when sharing information on any level of teaching. I am not yet a teacher, but I can see the potential.

Doodle is a collaborative tool that helps in scheduling meetings. It's especially useful for larger groups who need to meet. This would be helpful for study groups in particular or older students with jobs, sports, and/or family obligations.