xournal - Lightweight notetaking and sketching app.
Stickies - Stickies is a PC utility written to replace Post-It-style notes left stuck to your monitor.
GoodNotes - GoodNotes lets you take notes and annotate PDF documents.
Scrawl - Scrawl is a notes taking and memo app that lets you keep track of the things that are important for you, like daily routine tasks, projects, reminders, calculations, or accountability of someone.
Stylus Labs Write - Write is a word processor for handwriting, designed primarily for tablets with an active stylus.
Pystickynote - Stickynotes for your desktop easily from the command line.