Take the hobby you love and do it for money...from home. The number of possible types of crafts you could make is endless--knitting, jewelry, scrapbook, pottery, ornaments, textiles and so on. To make this work, though, you have to not only create a quality product but you need to know how to market it. You can go the old-fashioned route and take your wares to craft shows and flea markets or use the Internet to expand your options. With online options like Etsy and eBay, your potential market is worldwide, but so is your competition.
Today, if you're at all serious about succeeding in any endeavor, whether online or offline, you have to deliver enormous amounts of value. Yes, you have to do the most amount of work for the least initial return. This is especially true online. Why? Because it takes time to build authority and create an audience, two primary ingredients necessary to succeed in the wonderful world of commerce on the web.
The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you.