Of course—the only reason I didn’t do so is because I didn’t want to bore people by repeating things I’ve harped on about before on this forum. 
Here’s a post summarising how and why I use DEVONThink to import Day One journal entries.
Aside from that I have an AppleScript database for storing snippets of useful code, another database for matters relating to management of the apartment where I live and a personal database for storage of receipts, medical information, bank statements and sundry other personal information. I also keep a “manuals and guides” database where I store pdf manuals and guides to software and odds and ends of hardware (have you ever tried to remember how to program a plant watering timer from one summer to the next? 
).
The joy, of course and in essence, is being able to find everything quickly and easily.
Edit: I should have made it clear I started simply with my personal database.
Stephen