Somewhat apocryphally, ol' Honest Abe once tamed the disorder of his Springfield law office with a pile of papers labeled "If you can't find it anywhere else, look here."1 This too could qualify as a commonplace.
By no means a pioneer of the practice, Isaac Newton famously kept a commonplace book, which is called his Waste Book, wherein he recorded all manner of musings and observations. Sitting on his desk, large and in charge, waiting for the quill to stain it with brilliance or utter drivel, it was his only notebook at first. It became thousands of huge pages long (~2181), many of which contained work that ended up in the Principia, the Laws of Motion, and the Theory of gravitation.