I found this on the net. A guide by Jessica Hische to those who have no idea whether to work for free or not. Here's a road map:
Should I Work for Free? (http://www.shouldiworkforfree.com/)

Copy of the Image here: http://www.aphotoeditor.com/wp-content/uploads/2011/01/workforfree.jpg

Never leave home without it.

More discussion on this chart here:

http://www.dvinfo.net/forum/taking-care-business/490209-handy-chart-should-you-work-free.html

Now THAT was funny!