EasyBib App for iOS
'Create accurate MLA, APA, and Chicago style citations in seconds by scanning a book bar code or by typing the name of a book. Build and manage your works cited. Once done, email your citations and then export your citations to EasyBib.com's popular bibliography management service.
Works best with iPhone 4.
Also works with iPad and iPod Touch, but camera on these devices requires that barcodes need to be held steady and at a proper distance for the scanner to pick up.'
This is a free app