Let's be very clear about where NDAs are appropriate and inappropriate - An NDA is very appropriate in class (A) where it concerns the protection of the content of the Intellectual property.  Signing Tables, Certificates, Source Code, Research Studies, etc...  Without an NDA of some form, either in the form an employment contract, or explict "NDA", an employee would be free to tarball 500 Gigabytes of intellectual property and take it to their next employer - walking away with all the hard earned IP of a company that may have spent millions of dollars, years of effort, and entrepreneurial capital in developing it.<p>An NDA is completely inappropriate in class (B) when it comes to protecting ideas/concepts/market sizing/future growth that will be exposed in an employee interview, investor pitch, or press interview - all of that is typically just brainstorming by a few smart people over a week or two, has no more or less value than what might results from any other smart people of the same caliber brainstorming.<p>Depending on whether you are in class (A) or class (B) you should, or should not sign an NDA.