How these programs work:

There are a number of ways in which HYIP make money for you:

They can give you some typing job which you can do in your free time.
When you are in cyber cafe, you get paid just for keeping one website open, while you are working on some other websites.
You get paid for credits you earn for browsing.
They invest the money earned from your work in online / offline markets or in stock exchanges and pay you dividend.
There are a number of different theories on which HYIP work.

Which are the HYIP?

There are different programs that you can join -
eGold,
HYIP.biz,
surfloot.com,
automaticmoneyvault.com,
income.nu,
clicknmakemoney.com etc.

The bottom line:

Even though these programs use different methods to make money for you, there is no harm in not trying out these HYIP programs if you can take care of your greed and finances.