Hosting your own services. Preferably at home and on low-power or shared hardware.
Also check out:
I use this as my dev diary. Pretty neat software with a solid base.
Can you share and edit a note with multiple people?
I liked it when I tested it but just like Silverbullet (another interesting self hosted note taking app) there is no offline mode/offline storage. I keep my home server only available locally, so I need notes stored e.g. on my phone as well and cannot rely on connection to my server.