I came across this site (a bit by accident really!), but it might be of interest to some members: www.busmiles.uk

Its very similar to the idea behind railmiles.me for trains, but it uses bustimes to work out mileage on your bus journey and gives you some nice stats about what you've travelled on etc. 

It's in beta at the moment, but I was given an invite shortly after signing up and joining their Discord chat.