Hi Rollercoaster,
Funny you should bring this up, because I just posted a SharePost on this very topic. You can read it at http://www.healthcentral.com/adhd/c/all/?ic=4019 . It's titled, "When Having a Bad Memory Can Be a Blessing" and it's about knowing how my awful memory affects how I recall - or fail to recall- important events in my life.
In the post, I suggest keeping a blog, but a diary will do just as well.
At any rate, you aren't alone!
Terry