I'd like to be able to find crags around me, look at the grades and photos.
Be able to log a climb, at the crag its self, upload instantly to the app/site whilst you're at the crag.
Find users around you. It would be awesome if you could search, users near me now or recently. Say you could "check-in" with a message. "Martin is at Frogsmouth Quarry in Runcorn - 'I'll be here until 9.30pm, come find me, orange rope, blue t-shirt.'" - That would be good and useful I think.