To find a legit work at home job from a company. You need to find a workplace that has an office where you can work out of there office.
Some office jobs allow people to work from home. You just have to ask them.
Anything other than that I'd be weary about it.
You can work at home for yourself though by selling things online through ebay, or creating a blog, or other website and sell E books, run ppc advertisements such as google adsense, media.net infolinks or even sell your own advertising space.