Ways of allowing users to edit Tag Descriptions?

I’m looking to make my website (www.lessonsix.com) a little bit more informative.

At the moment we use tags for every artist we feature but for someone who has never heard of “artist a” or “artist b” the tag archives aren’t so helpful. So I’m looking for a wiki-esque system that would allow people to edit the tag descriptions – meaning the aritsts bio could be added and written by the users themselves. Naturally with an admin feature or at least something where I could roll back to a historic version like most wikis. Preferably allowing them to upload photos as well but not a requirement.

Is there a way I could do this?