If you have some creative talents, you could earn an income by creating something to sell online or at craft shows. Those who knit, craft jewelry or make clothes can start their own business, or just make some extra cash on the side without a big investment that a lot of businesses require.
I found a great article on Entreprenuer.com (link here) that provides some great tips on getting started. They also provide links to several directories to find local craft shows.
You may also sell your items online. You can set up your own website, or you can dropship for other sites. Dropshipping allows other websites to sell your stuff without actually having inventory. They just notify you of the mailing address when they have a sale and you mail it directly to the customer. (About.com provides a great description of dropshipping here)