Typically these type of proposals are less than favorable, but it is also nearly impossible for an individual to execute such a 'revolutionary' idea in an industry that requires significant resources to properly test in the market.

Also, often times, the first version of an idea isn't always THE success. Look at how whatsapp was sold for 16 billion, but when whatsapp started, there were companies like gogii that already had established a solid user base. The same with how facebook succeeded myspace, which succeeded friendster.

If someone would like to think they got a million/billion dollar idea that they'd rather not share because someone else would take the spoils, then I'd question whether they are serious about the idea in the first place. You'd figure an idea like that would already have been tested on a smaller scale in some shape or form already. Come up with an MVP and see if the proof of concept holds, etc.

I personally don't like the idea of middle men fishing for ideas from the public on behalf of their corporate overlords (better off pinging a few friends and bouncing off ideas), but I think some people also need to consider that sometimes it's OK to give up ideas if you're just going to sit on it and not do anything about it. Do your homework, make sure you get as large of a piece of that pie as possible when negotiating with other entities, and actualize the potential that will never materialize if you simply sit on it forever until someone else comes up with the same idea and reaps its rewards. This may come especially handy if you really do have a patent-able idea. Patent it yourself and sell it to the corporation, or better yet, negotiate revenue share/royalties. That way you give your idea but CYA while you're at it. Be smart.

That said, I think if I were OP, I would dig through these forums and see what people are complaining/wishing/hoping for, and come up with his own ideas on what to do. I'm building an app right now, and this place as some seriously good data points, and I don't even have to ask anything directly from anyone.