One of my worst travel nightmares is needing to pee and not knowing where a restroom is. Your problem is solved with Toilocator, an app that uses your GPS location to map out all the public restrooms near you!
When you are out of range or wifi or cell phone service you can still find your way around with Maps.Me, a great app where you can download city and county maps in advance and use them to navigate without internet connection!
GlobeTipping: easily calculate a tip specifically taylored to the country you're in, as well as the specific situation and bill total. Avoid cultural tipping faux pas with this free app!