Most of us imagine working 40 or so hours a week, and then earning a paycheck for that work. That is, in fact, how many people support themselves year after year. But did you know that it's possible to continue earning income--even after you stop working?

If you're looking for the ability to continue earning--day after day, or week after week--after just working once, you might want to consider some different forms of residual income.

Also known as passive income, residual income is money you earn for one single, initial effort. This allows you to continue generating income, and possibly increase your earnings, with little or no work on your part over time.

One example of residual income is a book author. After making the initial effort to write and publish the book, the author continues to receive income on that product in the form of royalties. So although the bulk of the work--writing the book--is finished and will never need to be repeated again, the income continues to flow. Actors and musicians are another example, because they earn royalties on their movies or music.

Another example of residual income is someone who owns real estate. In fact, if you're a homeowner, you're already generating residual income, although you may not actually be earning any money at the moment. That's because, for the most part, real estate increases in value. Since the value of your home will increase over time, you will have "earned" money during the time you owned it.

You can earn residual income through real estate in other ways, too. For example, you can purchase a building, house or apartment and then rent it or lease it. Your income will be the rent payments you receive on a regular basis.

Even a basic savings or investment account can be considered a form of residual income, since you earn money over time on an initial deposit.

Sales is one of the most common places folks earn residual income, especially if they're part of a direct sales program that allows them to bring in new sales agents underneath them. Many famous direct sales companies give you a portion of the profits from sales agents if you recruit them, and if you take on a "managerial" or advisory.

Affiliate programs are another way many people, especially those who are web savvy, tend to earn passive income. By establishing themselves as affiliates of other companies, such as retail websites or Internet companies, they earn a portion of the profits or a flat rate for referring customers and clients. Many webmasters simply post a link or ad on their site to generate this extra income.

With a little ingenuity and creativity, also anyone can begin generating residual income. Just choose a method that best suits your personality and resources to ensure your success.