https://office.microsoft.com/en-us/assistance/HA011436411033.aspx (I saw this on sluper's blog entry.)
About a year ago I started using Onenote to keep a work log. It has been awesome. My OneNote log acts as the glue that ties the bug database, and source control system back to the people and experiences I can remember.
I keep a section for each week, a page for each day, and a simple list of everything I do that day. Whenever I finish doing something I jot down what I completed, and when I start something new I jot down what I intend to do. Every couple of weeks I toss the older sections into a subsection I named 'archive'. It is very low overhead, and the act of jotting down what I am doing acts as a great feedback mechanism. Am I getting too bogged down on something? ... I can tell because my list of items is less than typical.
The key thing for how I use my log is keeping the names of people (actually email aliases), bug numbers, changelists, and component names together. We have a great bug database that allows for complicated queries. However, this is not a query that the bug db supports: "Remember that bug I was talking to Azeem about (was it three of four weeks ago?) that involved some other team and the cpde - umm, what was that team?" My OneNote log rocks on that kind of thing. What were the bug #'s for all bugs that I talked to Jkeljo about? Again ... not tracked in the bug db, but that is tracked in my OneNote log, along with my thoughts about the bug at the time when I recorded it.
I've tried keeping a journal before and found I was just too lazy. (See my average number of blog entries for evidence of this.)
OneNote makes it so easy to keep this log I don't don't even think about it. This is not a lot of journal entries, it is simply a list. Each entry is the bare minimuim note I need to metally close out an item, or start myself on the next. Over time I've simply found it's effective to keep as many proper nouns as possible in each entry.
Go try it. How I am using it is just the tip of the iceberg, and I am extremely happy with how it works for me.