Surveys – many people get started with their home working this way and it probably needs little introduction, but if you sign up to a few paid survey schemes then you can earn a little bit of cash without spending your own. However, there are limited opportunities and calling it a business is stretching it!
Blogging – this is more realistic and if you have the time and patience you could run this as a full time business. Create a handful of blogs and start posting to them and working on their popularity. Once you are seeing decent traffic levels you should also be earning through affiliate links and Pay Per Click schemes and if you want it to be a full time business, you can just keep creating plenty of new blogs.
Drop Shipping – there can be a tiny amount of cost here, but so little that it is virtually investment free. You may have to pay to sign up to a drop shipping merchant (do not pay for a list of these sites, just do the research yourself), but what I did was to hold off on the payment until the first order arrived! Then you need to promote the products, which again is almost free if you are advertising them on Ebay. Not totally investment free, but almost and certainly a home business that can grow.
Stock Photos – if you own a decent camera than this is totally free. The only problem is that you need to be able to take high quality pictures, although the quality level required will vary depending on where you are selling them. Once you have taken the photographs you upload them to stock photo libraries, who will market them and pay you a commission. But some libraries will only accept the best of the professional quality images, whereas other libraries seem to accept any snap shot. It is up to you to find a library that you can work with.
Get Writing! – Do you know a lot about a subject? Do you feel confident that you could write about improving a golf swing, internet marketing, finding a cheap mortgage or whatever? If so, open up Word and write an Ebook. Convert it to a PDF file and then start promoting it. You could use a free blog and article writing to attract visitors and sell it that way, or if you do not mind a little investment, then sign up to a system such as ClickBank and have their huge team of affiliate also promoting your eBook for you.