Appcelerator Cloud http://www.appcelerator.com/platform/appcelerator-cloudservi...

App42 http://api.shephertz.com/

Kumulos http://www.kumulos.com/

Kinvey http://www.kinvey.com/

Apstrata http://www.apstrata.com/

Buddy http://buddy.com/

Stackmob https://www.stackmob.com/

Proxomo http://www.proxomo.com/

Iknode http://iknode.com/

Kii http://www.kii.com/en/technology

CloudMine https://cloudmine.me/

Applicasa http://www.applicasa.com/

MobDB https://www.mobdb.net/

Windows Azure Mobile http://www.windowsazure.com/en-us/develop/mobile/

FeedHenry http://www.feedhenry.com/

-- My favorite ones are in the order of preference following :

Appcelerator (currently using it )

App42 ( tried it )

Stackmob (tried it )

Kumulos