One of the best Christmas presents I have ever gotten was a Garmin running watch from my parents. It is a necessity to have training for any race! It tells you how many miles you have ran and your pace. You can also keep track of your heart rate. I have never used the heart rate monitor before, but I probably should. I tried it once, but I don't think I had set it up right.
My Garmin has logged a lot of miles with me and has gotten me through a lot of races. It has helped me achieve some PR's and step up my training.
I didn't have my Garmin when I trained for Portland and it definitely made keeping track of my mileage more difficult. As soon as I would get home I would hop onto the computer and map out my run on google to verify how many miles I had run. It was tiresome to memorize every street I ran down on some of the longer runs. Thanks to my Garmin, I don't have to use google maps for my training runs anymore.
You can purchase a Garmin at pretty much any sporting goods store. Costco has even carried them in the past. They range in price starting at about $100. Trust me, a Garmin is worth every penny!