I started blogging, like many people, to record the details of my life, and to be able to reflect on things as they occurred to me. Blogging is like meditation -- by being present in the moment and reflecting on it, we hope to gain some insight or knowledge from it (or at least I do).
But after a couple years of recording my days somewhat regularly, I sometimes go back and re-read passages and have almost no recollection of the events or feelings I am describing. This is to be expected, I guess. If I didn't write these fleeting momentary thoughts down they would be completely forgotten almost as soon as I had them. Generally, what I'm capturing are temporal states of mind that aren't meant to last.
However, I think blogging is also screwing with my long-term memory.