Aside from a good pair of Running shoes a GPS watch and Nipple tape.
2 of the most essential Running Tool that a runner should have is a Running log book or as i call it " Running Diary " and a " Shoe Mileage Diary".
A Running Diary is very important to monitor the distance you run for the day / week / year, body weight, what food you ate, weather, what shoe you wore but most of all how you felt during your run.
In my Running Diary ( asides from the above ) i would indicate what my mood was that made me run faster or slower.
But most important if i am injured i would write it in detail location of the injury what might have caused the injury and what am i doing to get rid of the injury ( ice, stretching , cut it out, etc. )
I still have my Running Diary since way back in the year 1981.
Sometimes when i would go over them or just to reminisce
I notice 2 things
1. My passion for running has never faltered. The high i felt during my first run in May 30,1980 is still very much the same as my most recent run :-).
2. As the years go by my Time is getting slower. :-(.
While for my " Shoe Mileage Diary " i would just indicate when i purchased the shoe and the mileage. I would write the mileage in pencil because it changes every time i use them.
So start the year run by having a Running Diary and a Shoe Mileage Diary you don't have to buy 1 you can create one to your own specification.
2012 will be a good Running year.
Sample of my 2011 Running Diary
Sample of my Shoe Mileage Diary
Really messy and scribbles but it works for me