Free-hand Pen Tool
A free-hand pen tool would be in Adobe's best interest. This tool would allow users to mark a PDF with a digital pen of sorts.
Other document editors that are inferior in many other ways have been winning out with both myself and many other consumers because of the free-hand drawing & annotating capablities.
I support the idea fully. Many users have a digital pen. It helps draw and put own notices on pictures and text. I wonder, comparing to other free available pdf software, that Acrobat reader doesn't support it at all. If you tried to use digital pen with the Reader once, you understood what I mean. It's terrible. I'm forced to use other readers.