Do you have specific knowledge about an area? Then write a digital book about it (Or ebook as it is commonly called) and sell it. Have a hobby? Write about it. Got a child? Write about how to cope with being a parent.

If you have a decent brain in your head, then you have potential to make an information product.

Create a service:

This is a lot more expensive, depending on what you are doing. Sometimes you will need a programmer to sort out all of coding for service. But if you can pull this off, then you should be raking in dough. However, I would definitely stick to writing an information product first, then once you have accumulated lots of money form this, start a service.

Create a content website:

Creating a content website is cheap to do (If you're doing it yourself), but is very time consuming. However, once you have plenty of content, which is search engine optimized, you can put ads on there and hopefully make a killing.

You can create many pages full of content, then display google's adsense ads on there. This means that you wont have to handle delivery of ads yourself, or worry about advertisers not paying.

Create an affiliate website:

This is similar to above, but without displaying ads.

Write plenty of optimized articles in a specific area, then go out and find someone with a product, become an affiliate, sell it on your website, and earn a commission.

What you want is an army of people actively going out and telling people about how great you and your website are. This will ultimately lead to more sales.

How To Do It

When you create an affiliate program, you must teach each individual affiliate what you want them to do, spell it out nice and clear. Then tell them HOW you want them to do it.

This might sound like a lot of work, but not necessarily so. You could just do above, and put it into an autoresponder.

That way, whenever a new affiliate signs up, they will receive a handy dandy guide, giving them all information they need so that they can start right away.

Also, it's a great idea to include an FAQ (Frequently Asked Questions). This will make it much easier for them to understand what you want them to do. Be sure to list every possible question that could pop into their heads, this will also reduce amount of email support you have to carry out.