Organize your photos by the date they were taken in a chronological hierarchy of folders for years, months and days (e.g. 2008 > 02 > 02 for photos taken on February 2nd, 2008). Create logs with brief descriptions of each date for quick references (e.g. "2008.02.02 - Groundhog's Day at Punxsutawney, PA"). I like to keep separate monthly logs (simple text files under the each month's folder) and yearly logs with highlights (under each year's folder) but experiment to see what works best for you.