What’s The One iPhone App You Can’t Live Without?

According to All Things Digital’s Media Memo, there are 6.6 million iPhone apps currently being sold each day, Peter Kafka wrote:

…let’s note that the velocity of apps Apple (AAPL) is delivering is increasing: It took Steve Jobs and company a little more than a year to serve up the first 1.5 billion apps, which averages 4.1 million downloads per day. But Apple moved the next 500 million apps within 76 days. That’s a 6.6 million-per-day average.

Today Apple sent out a press release stating that two billion apps have been downloaded to date. There are now 85,000 apps in the App Store.

Not including the apps that iPhone includes, what’s the one app you can’t live without? Why?

Photo by: mind on fire