In the late Middle Ages, scholars started using “Commonplace Books” to collect knowledge of all kinds. These were not journals, but more like scrapbooks to gather quotes, letters, scientific formulae, and personal thoughts. Famous commonplace books were maintained by Thomas Jefferson, Francis Bacon, Henry David Thoreau, and Mark Twain. Sherlock Holmes himself solved a number of crimes by referencing his commonplace books!
This website isn't so much a blog as my own digital commonplace book where I keep items of personal interest.