There are literally thousands of companies that are willing to pay you to help them sell their services or products. Some will pay a commission on sales, some will pay for a click through, some will pay a flat fee for a sale, and some will pay on a combination click throughs and commissions from sales.  Some of these companies advertise nationally and some don't advertise.  My advice would be to pick a combination of companies.  The companies that advertise, don't usually pay as good as those that don't, However, the name recognition will draw more people to your site and increase your traffic, and sales.  Choose companies that fit the theme of your web site.  My favorites are those that will pay you a residual income. (services that you get paid monthly usage on for a one time sale)    The following are affiliates that pay like that:

1.  Cognigen Communications  ( earn commissions on long distance, paging, Computers, call back service, Cellular service, satellite TV and more)  NO COST to join.  This one is an excellent choice. Services are reasonably priced and easily sold. Great support from the company.