As a student, I am often refered to .pdf documents for additional reading assignments.  It would be nice to have the ability to highlight and add my own notations - for my own reference - as I read.  This feature is currently not available unless the author provides permission.  However, I don't want to make corrections and return them to the author, I just want the ability to easily find information that is key to me.  

I would like to see the edit/markup features available for all documents.  If not all of them, at least allow me to highlight.

Thanks!