Craigslist is a very powerful tool for a blackhatter. Craigslist (now known as CL) requires very little to no investment to get going. You have a highly trafficed site and you can promote a variety of things on it.
PVA's aka phone verified accounts allow you to post in sections such as jobs. You can get these for around $3.50 on bhw.
Networks generally frown upon CL for traffic. If you get a chill AM (Affiliate Manager) he/she will usually allow you to run CL traffic as long as it converts for the advertiser. Advertiser's are the guys who essentially write the cpa network's paycheck. They make a commission off the you, the affiliate. Essentially, they act like "the house" in the casino. If there is a dispute between the affiliate and the advertiser, 9 times out of 10 advertisers wins. If your promoting a sale campaign, you will have a much better chance of getting paid.