Voicethread is a useful, fun and simple tool for playing around with images, text and audio in ways to add and share meaning(s) with others.
They describe it as follows:
:A VoiceThread is an online media album that can hold essentially any type of media (images, documents and videos) and allows people to make comments in 5 different ways – using voice (with a microphone or telephone), text, audio file, or video (with a webcam) – and share them with anyone they wish. A VoiceThread allows group conversations to be collected and shared in one place, from anywhere in the world.
At the moment it is free and you can see it would be very useful for any of the educational style, participatory community/local history projects that museums do so well. Also, for teachers, museum educationalists or kids just playing around.