Tell me your scratch-your-own-itch ideas

Scratch-your-own-itch is usually one of the most recommended approaches to finding a problem to solve. I have not been able to identify any "own itches to scratch" (except for some note-taking or organization issues). Being an engineer in a large team who works mostly behind-the-scenes, I feel like, I might be lacking exposure or maybe approaching at it wrong.

I want to hear stories of how you built a business by scratching your itch (how did you identify it, what was your background - dev/business/product/marketing, etc.)