I run wearing a Nike+ sensor. My husband got it for me last December, right before I dropped the "I think I'm going to run a half-marathon" bomb. I really liked the freedom of not needing to map my runs before I went out, or worse, running the same rectangle around my house. But recently, I've been thinking that the distance isn't quite accurate. My Bronx Zoo 5k was recorded at 3.48, and my half was over 14...yeah, that was a pretty big clue. Today I used for a 3 mile loop around my house. The Nike+ picked it up as 2.87 miles. Not a huge difference really, but I guess I'll need to recalibrate the sensor tomorrow. I don't want to do any math here, but I finished 2.87 miles in 27:19, which is really excellent time for me.
Running errors aside, this morning two of my colleagues told me that they also registered to run the NYRR Women's Mini 10k in Central Park. Exciting!