Here's a video showing how you can improve your DSLR audio using RØDE's iXY iphone Microphone system
The RØDE iXY stereo microphone is a half-inch cardioid condenser configuration with the two capsules arranged at 90 degrees to each other for accurate stereo imaging. It comes with an iOS app (with a free version and a more advanced one for $5.99) that adds a range of useful adjustments such as high and low pass filters, as well as non-linear editing and one-touch publishing to SoundCloud, Dropbox, email and iTunes.
We've recently looked at the background to RØDE and now here's a video of how using their iXY system beats the internal microphone on a DSLR. This was always going to be better, but it's striking to see/hear the difference.