I mentioned an idea above to create an online store but you could also just declutter your house and sell things you no longer use (CDs, DVDs, kitchen appliances, etc.). There is a platform that makes this really easy, it's called Decluttr. You download their app and scan the item and Declutter will tell you the price at which to sell. Check out Decluttr (or for more information, read our Decluttr review!) Listing items on eBay is of course another option, sign up by going to www.eBay.com.
…Marketing an eBook is definitely the hardest part. Ebooks have exploded in popularity and the market is unfortunately saturated with crap from people who thought they could write a quick eBook, put it on an affiliate network, and make millions. However, if you CAN find a good way to market (or possibly have others market by having it listed on affiliate networks) then an eBook can be a great way to make some residual income.
If you are a professional photographer or have a real flair for photography, then selling your images on other sites could be an idea. This could be done alongside your own photography site, as it is a good way to help get your work viewed by a wider audience. There are numerous stock image websites to contribute to, but choosing a popular high-end site like Shutterstock should ensure your photographs make you some money.
Outsourcing is the name of the game in today's business world, but not all the work gets shipped out to Bangalore. To get matched up with a client looking for remote assistance, sign up with Solvate (solvate.com) to become a "talent member." Name your target rate (think $20--100 per hour, depending on the skill level of the work) and lend your services as an accountant, designer, virtual assistant, writer, bookkeeper or techie.