I found these apps and tips useful on a recent trip to Europe.
I used Pixter and Google Translate (requires internet) occasionally to translate narratives in museums. I haven't tried Word Lens which is recommended in the Rick Steves' Smartphone Apps article.
Google Maps has a feature where it will capture and hold map data for an area for off-line use. This involves getting the area in the Google Maps display, then entering the phrase “ok maps” in the search field. This can be especially useful for rural areas that are not covered by metropolitan off-line map apps such as Ulmon PRO CityMaps2Go. I depended on CityMaps2Go more in the past when I was traveling without cellular data access, but it was still useful at times to have these data rich searchable off-line maps on the phone.
GoodReader is a power house app. I put copies of lots of notes and documents into it before the trip. This included copies of hotel, plane, train, car reservations; insurance documents, Verizon information. GoodReader has a feature where it can capture information from Safari. For example, there’s a ten-page PDF guide and plan (map) that you can find on the Louvre web site. GoodReader can capture that PDF for off-line reference. I captured the text from several Wikipedia articles on topics of interest that came up during the trip, good reading on the plane home.
Related to translation dictionaries and apps. I had good experiences with a Collins Spanish-English dictionary in the past so I purchased the Ultralingua French-English Translation Dictionary and Verbs for $19.99 despite reviews that said certain search words (e.g. “gar”) crashed the app. I assumed or hoped the problem had been fixed in the interim. Unfortunately not. I got no response from the vendor so I obtained a refund from iTunes Store, but then could not review the app because I no longer owned it.
German English Dictionary + by VidaLingua worked well.
Fast Talk by Lonely Planet - Phrasebook is quite beautifully designed. The “free” version is a stripped-down demo so it is not useful by itself, you need to pay for content. I purchased the add-on that provides French, German, Italian, and two flavors of Spanish. The app contains a good set of phrases, but it’s not super extensive. The implication is that the editors chose to hone the content, keeping it somewhat lean to make the app more user friendly. One feature that deserves very high marks is that the app presents formal and informal variants of a phrase in a simple elegant manner.
Use your camera to capture portable information. Heading out from your hotel to a restaurant and you don’t want to carry Rick Steves, shoot a photo of the area map and the page or two describing the restaurants you’ve highlighted. Bus stops often have lots of key information: list or diagram showing the names and order of stops, the daily, weekend, night schedule. Take a shot of this information to help you anticipate where to get off the bus and to plan when to catch the bus for your return.