One great way I've discovered to make a little cash on the side is by participating in market research studies. Basically you are entered into a company's database and they call you when they have studies that fit your profile. If you qualify, they invite you to participate in the study. It consists of anything from an hour long discussion to taking a product home and trying it. Typically the pay is somewhere between $50-$100. I'll take $50 to sit in a room and tell you what I like about the diaper brand I use!
It's difficult to qualify for the studies on a regular basis. They like to keep their panelist pools fresh, so they normally won't accept someone who has participated in one of their studies in the last 3-4 months. I have signed up with several different companies in order to spread this out a little bit.
This week is quite a money maker for me. I'm participating in studies with MarketVision Research for laundry detergent, Evenflo for baby carriers and AIM Marketing for liquid dish soap. I once was involved in a Procter and Gamble study on dishwashing detergent that ended up meeting one hour once a month and paid $60 each time. Now that's a nice little money making plan!
If you're in my area (Ohio), there are several options available, including Qfact (which offers childcare!), Procter and Gamble - Consumer Village and Discovery Center and MarketVision Research. There are others throughout the country, so if you know of any, please comment and let others know!