Just as much as I know
I have worked at home now for a couple of years doing various things. If you have ever been interested, making small flash games with ads, or with a sponsor is a good way to get a small amount of royalties. Same with developing small, free apps for mobile devices, with a thin ad bar at the very bottom.
Most of my money comes from transcription, which is an amazing job if you can land one, and I can link you to a few reputable companies if you'd like. The best thing about these type of jobs is it's very steady work that you take and complete on your own time. My boyfriend and I already live pretty much the same life as when his father was retired and mother was semi-retired (both in their 50's, they have now taken up jobs after buying a new home, and are working until they sell their current house and can leave the state to fully retire).
I also used to work an hourly job at home for a short period of time, but I just COULDN'T handle it, because it was the dreaded customer service. If that's something you can handle though, I can also refer you to companies that hire at home customer service agents. Most large companies are finding it cheap and efficient to hire American at home-ers. The hourly pay itself for me wasn't very good, but my pay was a bit more than doubled each time through commissions.
Finding my own clients to work for has been my most lucrative, but most time-consuming work as well. If you're wanting to feel a lifestyle that's really easy going, finding a work at home company that will just funnel you nice, laid back work, with a deadline however many days in the future, which you can choose however much or little of as you want, would be my recommended choice. But if you're looking for something more stressful, which also pays more, head out there and market yourself!
There are different sites better suited to different areas of skill. LinkedIn, Twitter, and Facebook are almost a must if you're going to come out as an individual in any area. Etsy is a great place to go when marketing your art, while other sites like Elance are better suited for business.
As far as finding those laid back jobs, I have found searching for work at home moms' sites works very well. They have good, verified information often.
The best grouping I've found so far of legitimate work at home jobs you don't need to pay for is at
Working From Home - Getting Started Working From Home - Finding a Job When Working From Home
They provided me a lot of really good resources and info about what to expect when starting to work from home, and they also have links to different companies that hire people at home.
Anddd, I think I've put everything I can think of at the moment there. Honestly, anything can be a work at home business if you make it one. You can even be someone's personal assistant from your home desk. So long as you're never paying the people, you've got nothing to lose!