Aussie-developed service Rome2rio has long been a Lifehacker favourite for its ability to show the full range of travel options between any two locations: flying, trains, buses, boats and more. Now you can access the same features via an iOS App.
The same search options are available in the app as on the site: you can enter any search, see a range of potential travel options and then see the route timings broken down. You still need to shop separately to purchase those fares, but it's excellent as a planning tool before you start locking down options.
Rome2rio is a free download for iOS devices. rome2rio also plans to license the source code to other mobile app developers; here's hoping an Android version emerges soon.
Rome2Rio [iTunes App Store]