Is there any website where you can sell out of box ideas?

Hi Varun, to make money out of your ideas, visit http://www.inventhelp.com/ This site help inventors with a product, or even an idea to reach the potential market. An idea dosen't always need to be a product. There are product designers, who design a product based on the submitted idea. Here's a sequence

Idea Originator -> Product Designer -> Producer/Financer -> Market

Also, if your idea is Innovative, you can contact a company to sell them the idea. But before showing them the details, you can get them signed a non disclosure contract, so that even in case they reject it, they don't use it. Patents also come for rescue in such situations.

you can get a job at a 'think tank' where you basically think and solve problems that someone gives you. but usually you need very good college degree and need to be insanely smart.