I'd say my nerdiest app is Logmein and the ability to control my PC via my phone. If you go to
www.logmein.com with PIE, it will give you the option to download and install the program (which is a .dll).
Surprisingly, it's come in handy a few times when I wasn't near a computer but needed to email a document to a coworker. Not super easy on such a small screen, but still works!