A wiki is a good way of keeping track of all the things that you've learned over time through notes and references.
A wiki doesn't always have to be on a server (like MediaWiki in my case).
A good desktop wiki alternative is Zim. It has a good WYSIWIG editor with plain text storage (no database).
Wiki pages in Zim can be exported to Markdown (pandoc) format and then converted to whatever format you want using the Pandoc tool if you want to migrate to a wiki on a server.