Take a look at NetStash. It's a travel app that lets you download entire websites for offline reading when you are for exampe on a flight without WiFi or just in an remote area without any internet access. Great free alternative to spending $$ on magazines for your flight.
Link to NetStash app on iTunes.
I used Triposo a bit.....not bad for destination guides since I was unable to carry any destination guides. Hotel Tonight is another one that for now, is not yet "everywhere" but they are adding locations swiftly. And while it may not be an actual "travel app" I find that Skype is very helpful for staying connected, when needed, for folks who can't Face Time.