Free and extensive iOS 5.1 PSDs for designers. Worth booking this blog since this Toronto based outfit have been doing these things since 2008 and don't look like they'll stop soon. Plenty of other good design resources to be found here also.
Arq lets you cut out the middle man by allowing you to backup files to your own Amazon S3 account, in exchange for a one-off license fee. As used by Nylllon to handle around 60GB of data, we can't recommend this highly enough.