If you own a home and have extra space you're not using in your garage, or maybe a side driveway, you could rent that space to people that need to store their boat or RV. The website JustPark.com allows you to rent out your driveway or garage to others and collect payment online. It's very easy to use and a great way to make some extra money on a space you don't use.
Freelancing is the next best thing to being paid more for your full-time work, because professional work always pays more than unskilled. To find opportunities, let former colleagues or other personal connections that you’re available for freelance gigs. (Here are some ideas on how LinkedIn could be useful for that.) Or, post on marketplaces particular to your field. For instance, Mediabistro, a journalism site, allows freelancers to post profiles of their experience and services. Though these are more up to chance, designers can bid on jobs at 99Designs.com or submit a design at Threadless, to see if it will be crowdfunded. Elance-Odesk also lists many freelance opportunities, and you can also post your own services on Fiverr, although some freelancers say these services create a race to the bottom on fees and so are not very lucrative. If you're new to freelancing, here's how to set your rates, and here's how to negotiate raises with clients.
I recently met a woman who earned quite a bit of money as a very part-time chef. Once a week, she would go to someone’s house and prepare a homemade meal for their family, then do all the dishes and cleanup work. This gives the family plenty of together time, while putting some cash in the woman’s pocket. If you love to cook, this can be a great opportunity, but you may have to put a lot of effort into searching for clients.
Take advantage of your strong typing and computer skills. If you are a fast and accurate typist, if you are great at creating interesting presentations with sophisticated graphics, or if you excel at creating tables and graphs to represent data, you may be able to get paid to teach and help other students with their assignments and hone your own skills at the same time.