A few weeks back I stumbled across a tweet (which I unfortunately cannot find to give credit to) that talked about the benefit of keeping a dev diary.
At the same time I was reading Getting Things Done (GTD) so I felt inspired to take note of everything related to development that I do during my day to day time - this would satisfy the criteria I had for my GTD system, along with trying to emulate the success the original tweet was referring to.
I don't have a fancy system as such, rather I have a text file that is distributed between the numerous desktops and laptops I have access to. Here the file is synced, so I should always be up to date. Dropbox handles this for me.
Each day I simply make a note of anything I think "I must remember that" or anything that happens to be useful, interesting or new. There is no complex system to this in order to keep in aligned with GTD, new points are simply appended at the bottom of the file. At the end of each week I simply group up related notes. For example, if I've got a few bullet points about databases, I move these to fit under a "Database" heading. This system works for now, though I might have to re-asses this in the future. An example of the file is below.
Databases - Points - about - databases SOA - More - points ... #### Everything below here is a rough note sorted at the end of a week to fit under the headings above. If no heading exists one is created.
The most surprising thing about this, is that even on a dull day I absorb a lot of "stuff" related to development. Equally surprising is how awful my memory is regarding it. If I skim across the document now, I'm alarmed at the stuff that I would have forgotten had I not taken a note. It's quite possible that I would remember some of this information in the long term, but regular skim readings of the diary is proving very helpful.