I'm on strava - really for my own benefit in training and tracking exactly where I've been and how far. Club wise I'm in Type 1 Diabetic which features a lot of the pro riders from Team Novo Nordisk. The distance and elevation of those guys is incredible. I also recently joined Team Blood Glucose.
I sort of agree with
@Auckland Canary as although I try to not let it, strava can sometimes make you chase segments rather than just enjoying the ride.
I usually take a look at flyby - it's feels a bit like stalking though!