Just read, "Making Money off Ideas" in Farm Show, vol 34, no 4, 2010. www.gismoplans.com is a website where you can upload your plans and contact info, and people get to see your ideas and potentially buy them. 'Tis a resource for inventors of all sorts.
You can also do "licensing" in which yu sell your ideas to companies and then they give you a roalty when they seel some of whatever it is. I have been looking into this for some time and am going to a convention for this soon.