Five Perfect 'Spare-Time' Online Businesses

Alternatively, you could take a look at your hobbies and other things you enjoy and see which affiliate programs are a good match. As always, do your research to verify the viability of your market. A good place to look for ideas (and downloadable products just waiting for an affiliate) is ClickBank.com.

4. Blogging: This business is best suited for folks who enjoy communicating about a particular subject. Think of blogs as journals of sorts. Although you can have a personal blog, writing about a particular topic will have a higher chance for financial success.

The range of topics is virtually endless -- photography, sports cars, parenting, dieting, star gazing, the latest gadgets, Hollywood gossip -- you name it, as there are blogs on just about everything you can imagine. Don't worry about competition. Folks who read one blog are apt to read others on a topic they're passionate about, as long as you have something interesting to say.

Once your blog starts getting traffic, you can make money passively with things like AdSense (Google's (GOOG Quote) ad revenue sharing plan) or actively by doing a little bit of affiliate marketing. You can see both types of moneymaking strategies at SparkleCat.com, which is a blog about a person's cat. What makes it interesting is that it's written from the cat's perspective and often refers to her "human." At the top of the page are Google AdSense ads, and sprinkled throughout are suggestions for things like cat furniture and premium cat food, which are tied to an affiliate program. Pretty cool, no?