(1) Sometimes good notetaking apps get ruined over time. I was a fan of Microsoft's OneNote for a while until they stopped saving notes in a well-documented XML format and kept all the data in the cloud. Microsoft also worked hard to kill OneNote by shoving it up every orifice of the Windows 8 user: print something? the default it is to save the printout to one note? Look for an application on the taskbar? Microsoft shoved three icons for OneNote onto the taskbar?

Microsoft never seems to learn that this behavior is perceived as harassment and that if they push a product too hard, even a great product, people are going to be angry that OneNote is opening when they wanted to print something to the printer, all they are going to think is OneNote is crap and they want nothing to do with it.

(2) Personalized full-text search is a tough problem, since Google came out nobody has been satisfied with the results they get from other full-text search products.