I read the title and went into a panic! Heh... don't scare us like that!
We have room on our electronic timesheets to make notes for each entry. I basically keep a daily log there. Sometimes the entries only contain something simple like "Worked on ticket # 12345" and sometimes they contain a more descriptive narrative with other facts and opinions. It's not a diary but it is a place where I can call up important facts about the year.
I also keep a running list of personal accomplishments, goals, and failures for the stuff that's useful on a review or to answer the "If you could change one thing, what would it be" question that I frequently ask myself. As with anyone and everyone else, I've had some rather tempting offers both challenge-wise and pay wise. I've also made some leaps in the past that didn't turn out the way I thought they should so I'm very careful about all temptations. Like you, I'm convinced that I've found/made my dream job and, although I'm reminded every day as to why it's my dream job (something or someone good happens more than once a day), I love the confirmation I accidently get when there's something new to add to the list.
--Jeff Moden
Change is inevitable... Change for the better is not.