Commission Junction Program
About
Commission Junction is NOT a CPA program. However, I will include it here for comparison. When you join CJ you have to apply for each offer individually and then wait for that company to approve/deny you the opportunity to promote them. Also, the commission that you get may be extended by each company, meaning if you get a $100 sale from offer X, that company can choose to extend your commission for another month, and you will have to wait 2 months in order to get your commission, unless they cancel your commission altogether of course, after you've waited 2 months.
The Sign Up Process
Commission Junction will verify your websites. They also have a quality check robot that scans web pages from which you refer visitors (You can see this in your server logs).
Interface
Once you login to CJ, you have add a few websites from which you will be sending traffic. Then once you pick an offer you will have to pick from which site you will be promoting that offer and that's how your tracking will be handled.
The Interface is well made. Offers are broken down into specific categories from which you can search and sort in a variety of ways.
Affiliate Support & Promotions
You do not get an Affiliate Manager with CJ. Nor do you get quality affiliate support. I submitted a support ticket once and had to wait 4 days for an answer. Other webmasters have complained of worse response times.
However, you do get to work with an affiliate manager from each offer. Each offer provides a contact who you can email and run your specific inquiry by.
Promotions -- CJ has a TON of tools. A lot of banners, pop-up codes, and etc.
Offers & Offer Payout
This is perhaps the biggest upside to CJ -- all the big name sponsors that you can promote that other CPA programs just do no carry, like: Ebay, Zappos, Fossil, NetZero, LowerYourBills.com, and etc.
Payouts vary per offer, but like I said, a lot of companies that are with CJ just do not run with any other CPA program.
Something of note: the statistical data is not updated in real-time. There is a lag of several hours.
Final Word
Sign up for CJ only if you have to. Go with them if you want to promote a big name company that's not present elsewhere.
If you want to promote a payday loan offer, or a 'pay per email submission' offer, or a 'get paid to work from home' offer, or a 'refinance your mortgage' offer go with someone else, like Hydra Network or Azoogle.