I worked for a year at a company and training two people to do my job from a stack of my personal notebooks and insider knowledge was a nightmare. After that I decided to keep a personal wiki which was easily searchable. Having gone the .txt route in the past and found it wanting, I decided on the next best thing and went with a Tiddlywiki.
I document all processes I develop and additionally keep a journal every day, and one at a project level. It has more than once saved my butt working on multiple projects and has made me a better manager. I finally graduated from a Tiddlywiki as I ended up wanting to collaborate on entries far too often. A year into my wiki experiment I switched to MediaWiki and haven't looked back as I can simply add collaborators and more transparently keep track of contributions.
I document all processes I develop and additionally keep a journal every day, and one at a project level. It has more than once saved my butt working on multiple projects and has made me a better manager. I finally graduated from a Tiddlywiki as I ended up wanting to collaborate on entries far too often. A year into my wiki experiment I switched to MediaWiki and haven't looked back as I can simply add collaborators and more transparently keep track of contributions.
For others wanting to transition I made a little conversion script here: http://www.itp.uzh.ch/~corbett/projects/code/tiddlywiki_to_m...
Tl;dr Keeping a wiki as a developer: ~best decision ever.