Many companies will offer you an incentive to find them new leads and customers.  You become an affiliate of the company, and advertise its products and services.  In return, you get paid a commission for business you send their way.  To find out if a company has an affiliate program, have a look on its webpage.  Often there will be a link for Affiliates on the bottom menu.  As with any paying program, do you research to avoid unethical companies.  Affiliate programs are good because you can sell just about anything, and you don't need to carry stock or take payments from customers.

Here are some of the Affiliate Programs I have tried:

Kiosk Web Hosting

Kiosk offers reseller web hosting and a complete website development and marketing system.  You don't just get paid for your own referrals.  Kiosk pays on a matrix system, 10 levels deep.  This means that you earn not just from your own efforts, but the efforts of your upline and downline as well..

Click here for more info

DrinkACT

DrinkACT is my main business, but you can also run it as an affiliate program. All you need to do is become a customer agreeing to purchase a certain amount (personal supply) per month.  After that, any sales from the free website they give you will earn you the markup value and start to build your business.

Click here for more info
 
FriendFinder

If you are looking for a very slick, very professionally run affiliate program, take a look at FriendFinder.  This is several affiliate programs in one, all related to finding people for friends and for relationships.  You can earn $1 or more for each person you send to the site who signs up for a free account.  You can also earn lifetime commissions, bonuses and more. 

Click here for more info