I use my Spark blog as a place to journal my runs. I include the date and distance run in the title and place the specifics of the run and a summary of the run in the body of that particular blog entry. It gives me a quick reference to my runs AND I receive feedback from my Spark friends!
I track distance, time, average pace, splits, weather conditions, clothing worn and equipment used in the entry. I will also include how I felt, any new pains or discomforts I felt during the run for possible injuries that I need to watch. It gives me accountability AND gives motivation to others!