These are some of my preferred affiliate networks.  They are all completely free to join. Put up your links and start earning referral commissions. I have tried many programs, and these are the ones that earn for me and I have never had any trouble getting paid by them either. If you sign up for any of these, I would sure appreciate it if you would use my link so that I can get the referral credit. Thanks!

Logical Media - A new network with lots of great offers

OffersQuest.com - This affiliate advertising network offers publishers the highest payouts anywhere! Best campaign payouts in the industry, easy to use account administration, detailed statistics reporting, and real publisher support.

FreeTradeMagazines.com
Get paid to give away free magazines.

Calling Cards.com
Another good program. Just 10 free minutes to anywhere, even from cellular.

Bullet Ads
Another small network that has been very reliable for me.

Catalogs.com
Make money giving away catalogs

DirectResponse.com
Make Money!

Focalex Affiliate Program
Focalex Affiliates benefit from excellent payouts and great resources. This is one of my top performing programs.

Share A Sale - Find a sponsor for your web site. 
Get paid for your great content. shareasale.com.

Let shareasale.com find sales leads for you.  Only pay when it works!

Hydra Network
I just started using this network recently. They seem to have good publisher support.