I keep a work-log, every day I have a template which gets created via a macro:

     * DD/MM/YYYY
     ** Desktop Setup
     None.
     ** Meetings
     None.
     ** Tickets / Stories / Projects
     ** Problems
     None.
     ** Worked Hours
     #+NAME: hours-DD-MM-YYYY
     | Start |   End | Total Hours |
     |-------+-------+-------------|
     | 09:00 | 09:00 |         0.0 |
     #+TBLFM: $3=$2-$1;t%.1f
     ** END

I record commands, stories, meetings, and other things. These are very very very useful to me for reference purposes, and absolutely not the kind of thing you can search google for.

Having your own notes/knowledge-base/wiki is good because it is stuff YOU care about, not stuff other people have posted.