Ask HN: Do you keep a personal knowledgebase? With What?

Basically, I have this problem where over the course of time I misplace old data and documentation. This then adds hours to the time it takes to pick up on a project that I haven't touched in a long time. It seems like the sort of problem everyone else runs into and that someone has a solid solution that I haven't run across yet. Ideally, this would not be limited to software development. After all, it's nice to be able to lookup the code to a lock box rather than text someone at 4 am.

I have tried a number of things from paper notebooks, text files in folders, trello, google docs, various databases, and various wikis. Most of them have good things going for them but there hasn't been a clear winner in the decade or so I have been playing with this.

So, I thought I would ask what people use and what you liked about it.