An entrepreneur recently asked me the following question: "When you think you are sitting on one of those extraordinary ideas, how freely do you discuss it with others?" Here's my response:
After being involved in startups for the last 15 years, I have come to the conclusion that there are very few people you need to truly worry about. Once in a while, I run into someone that I just don't freely share (fully baked) ideas with. However this is extremely, extremely rare, and when it happens, I just wait until I am more certain of the other person's motives and integrity.
1) Ideas are like ears, everyone has two... Your idea is probably never completely unique; almost without a doubt, someone someplace else is thinking nearly the same thought... I have found this repeatedly; especially on the Internet. However quickly filing a super-cheap provisional patent is worth doing, if only for piece of mind. I personally don't bother with NDAs anymore (giving them or signing them). Most investors won't sign them either, as they see far too many duplicate ideas.
2) Execution is everything... Your ability to execute is what really matters when it comes to beating the other guy (with the duplicate idea). There are so very, very, very few people that can execute (raise money, build it, take it to market, and grow it) that the benefits of sharing ideas with almost anyone (and getting critical feedback), outweighs the risks. Moreover if you meet the RARE person that can truly execute, he or she is usually executing on...some other idea...and does not have the time to do yours.
There's millions of entrepreneurs sitting on piles of NDAs and truckloads of patents or patents pending, but there are very few entrepreneurs that succeed on the web. 99.999% of the time, speed and relationships are more important than secrecy.
Now watch my attorney friends tell me this is bad advice...