I'm sure a lot of the people that use DA will have already seen this but I thought it was a pretty interesting video from Comic-Con.
It's a panel with Josh Wattles, Advisor In Chief at deviantART (a copyright professor). He talks about copyright and fan art law.

It's a 55 minute video, but I found it pretty interesting.

The article where this was originally embedded is HERE
You can watch the panel video on youtube (link below)
http://youtu.be/xKBsTUjd910

edit: He talks about copyright and fan art but he also briefly mentions copyright relating to your own work too.
Also if this is in the wrong place feel free to move it