All focus groups and online surveys are not created equal, so anything recommended here has already been tested and verified. Many years ago, I was on a focus panel for opinions on HGTV, and earned a crisp $100 bill!
If you have the time, a computer and/or telephone, market researchers are looking for your opinion and won't mind paying.
https://join.harrispollonline.com - earn points towards gift cards, magazine subscriptions, etc.
www.focuslinesurveys.com - pays you $5.00 just for signing up, then gives you many choices based on your profile.
www.focusgroup.com - gives a wide variety of things to choose from once you sign up and include mystery shopping, telephone surveys, focus groups in your state, etc. In some instances you can earn up to $150 just for your honest thoughts!
www.ejury.com and www.onlineverdict.com allow you to earn cash for serving on an on-line jury which helps lawyers with actual on-line cases.