I found a Google site that has a Master Content Mill List. Content mills are great eggs to have when you don't have any private client work. I have a few mills I work for on a regular basis.
Content mills are also great for individuals who are just starting out in their freelance writing career. I got my start with Yahoo! and I am extremely grateful to them for that. In fact, I still earn a nice residual income from the articles I wrote for them.
Just to let you know, I don't earn a penny from telling you about this list. I just thought it was a helpful resource and wanted to share it with anyone in need.
So here you go:
Master Content Mill List
PS. I noticed a few of the links are outdated, but there is still a ton of information here. I guess the author just adds to the list without checking old links.