On November 21, Princeton University Press will launch an iPad app version of the Barrington Atlas of the Greek and Roman World. See the press release below; there’s also a slide show of screenshots on the web site: http://blog.press.princeton.edu/barrington-atlas-of-the-greek-and-roman-world-app-available-november-21-2013/.
The upshot is that the complete content of the Barrington Atlas (100+ color maps of the ancient world), is available, but with integrated navigation and search functions.