Awesome Note
iOS | Android
($ Cost) Create and organize notes, task lists, and calendar appointments and back them up with Google Docs or Evernote.
Goodreader
iOS | Android
($ Cost) Document Reader with built-in annotation tools.
Notability
iOS | Android
($ Cost) Use Notability to take notes, sketch ideas, anotate PDFs, mark-up photos, record lectures, provide audio feedback and more.
Tiny Scanner
iOS | Android
Scan notes, photos, receipts, etc. into a PDF by simply using your iPad.
Wunderlist
iOS | Android
Wunderlist is the easiest way to get stuff done. Wunderlist is here to help you tick off all your personal and professional to-dos.