What are the best networks in your opinion for this? Also do these networks require you to have a site?
Check out the link in my sig. I have a ton of CPA networks listed that have paid me time and time again. They are very reliable and I have had nothing but success with them. Questions send me a PM.
For what? Campaigns? You can run CPA campaigns anywhere. I'd personally just do your homework and pick networks that have some kind of history to them and didn't just open up last night. They are known to close down and not pay people.
There are many good cpa networks on the web that have some good campaigns. What about the one already in your sig as you say that's the best affiliate program, lol.