Best free apps for smartphones

The free applications in the article are for iPhone, BlackBerry, Windows Mobile, and Google Android devices. I have many of these free applications on my devices, but also discovered a few that I have not yet tried so I downloaded and installed them as well. Keep in mind that a few of the applications, such as Evernote, can be used on multiple operating systems so search around for the application on other platforms if you see it on one in the article.
Even though the tagline of the article states, "Get more out of your jack-of-all-trades device with our top picks for every platform" that isn't quite true since Symbian and Palm were not covered. Palm is out now with WebOS coming online, but Symbian is still the world leader. Since the article did not cover S60 applications, I put together this article over at my Nokia Experts website.
Do you have any other applications that you highly recommend for readers to try out on your favorite mobile platform?