Now that all the serious answers have been posted.... I agree the phone apps work fine. Garmin works a bit better but if you aren't looking for cadence a Garmin 200 works just as well for most people and you can get one for $130.00 from Nashbar or most LBS.

Now for the less serious part. We used to have a saying here, if you don't have pictures it didn't happen. Now when someone says they have passed the local roadie club on their hybrid with panniers going up hill in the wind while drinking a soda we can say, without Strava is didn't happen. Plus if you get Strava Dudelsack will force you to join his club.