Some of them are Parse, StackMob, CloudMine, Buddy, CocoaFish, Kinvey, Kii (As told by German).
All of them support geolocation based data and offer services on different platforms.
I have observed some of their features :
Parse - schema-less; Cheap; basic analytic free; supports: push notification, user management
StackMob - with schema; basic analytic free; supports: push notification, user management, custom server side code
CloudMine -schema-less;supports: push notification, user management, custom server side code
Buddy: schema-less;supports: push notification, user management, friends system, has own places database,built in friends system, built in events
CocoaFish - schema-less;supports: push notification, user management, built in friends system, built in events
Kinvey - schema-less; supports: push notification, user management,
Kii - supports: push notification, user management, basic analytics free, Ad Mediation and Direct Ads
