Invention ideas

I am wondering where in the Internet should we find, or post for that matter, ideas that could be transformed into inventions by scientists, engineers and other magicians. Ideas can't be patented, as far as I know, and there are lots of ideas that could become commercial products or cool gadgets or used as imaginary objects in literature or movies. Could this be part of the free/public/copyleft movement? or would authors expect a voluntary retribution from those eventually making money from the idea, or just wanting to collaborate to the author? Whatever it may be, the case is that many ideas are probably wasted because they were never published.