I agree that you need to take that "risk" and share your idea with others. Just like you I also had the same dilema about my ideas. At one point I realized that having them stored in my brain or somewhere on a piece of a napkin will not do any good to anyone. I decided to air them out on a blog, still have a bunch to add but here is a sneak preview to show you what I mean:
http://innovationsforgrabs.blogspot.com/
The google ads made me 84 cents so far so it's a bonus too
:)
On the other hand, I decided to devote my efforts on starting my own company. I'm developing a software application that already exists in many shapes and forms. However, I found room for improvements and I believe that with effort and persistance I will succeed.