A DRM plugin would be most excellent and I'd like to throw it out there to you dev's. As an eBook author, I would love the security a DRM solution would offer. Right now, my books and tutorials are vulnerable and my business would benefit hugely if a plugin was designed to password protect my pdf's.

There appear to be many software solutions available for this already with numerous options for protection, however - they are ridiculously costly. Please consider this suggestion. I am sure many people would benefit from it :)