London for Less (free for iOS)
What it is: An app that helps visitors score 20 percent discounts at more than 150 restaurants and attractions in London.
How it works: After launching the app, travelers tap the Guide or the map to find discounts. After clicking "get discount," a screen appears with a bar code that a merchant scans to provide the savings. If you are in London, it will use your phone's GPS to show discounted food and sights nearby. Users not in London see a map.
Why it's great: Britain's capital is pricey, and this free app saves money without requiring users to pay a fee to get the discounts. The 20 percent discount is good for as many as six people. While offline, London maps are available to limit data-roaming charges. (I use Wi-Fi and turn data roaming off abroad to avoid outrageous international charges.) Beyond discounts, the app provides info about more than 12,000 points of interest. An onboard tube map shows where the stop is for a particular venue.
Why you might hesitate: I wish the app detailed admission prices and indicated whether a restaurant offers pricey or cheap eats. Alternatively, the app could provide a link to the venue's website for this info. But why hesitate when it's a free app that can save pounds in London?
Banff Park Companion from Mountain Apps ($4.99 for iOS)
What it is: An app to help travelers explore Banff National Park and Lake Louise.
How it works: Users can plan activities using the Guidebook or the index of mountains, lakes and points of interest.
Why it's great: The app is steeped with information from the author and Parks Canada, and it connects to Parks Canada's website for up-to-the-minute info about trail conditions, bear updates, etc. The app's author is a geophysicist and a Canadian Rockies interpretive guide, so geographical and geological data are included along with hiking and wildlife-watching tips. The app includes an offline map as well as a map that utilizes the phone's GPS.
Why you might hesitate: Two minor quibbles: The Parks Canada Web pages sometimes load slowly (taking 30 seconds), and an audio component would add some spice so hikers could listen to a bit of history about Banff or songs inspired by the area. (For example, the Golden Gate Bridge app includes historic recordings and suggests songs about San Francisco visitors can buy on iTunes.)
Street Food Vancouver (free for iOS)
What it is: An app that details the daily location of 49 food trucks in Vancouver.
How it works: After launch, users scroll through the food truck list to see which are open, or tap the map to see which vendors are nearby. The list indicates whether a food truck is open or closed. Green pins on the map show available food trucks, and red pins show those that are closed.
Why it's great: Whether bicycling in Stanley Park or exploring the city on foot, this easy-to-use app puts your finger on the pulse of Vancouver's food truck scene. Local favorites include Tacofino for fish tacos, Re-Up BBQ for pulled-pork sandwiches, and Japadog for its famous Japanese hot dogs, plus the Juice Truck. The app's map works offline.
Why you might hesitate: The app offers more detail with Internet reception, so I got more info in my hotel room with a Wi-Fi connection than I did out on the street with no data signal. But the outrageous cost of international data isn't Street Food Vancouver's fault. And it's still useful with only the offline map.