Currently sitting atop the top free app spot in the App Store is an app called Flipagram. The concept behind the app is to help you create what amounts to a slideshow using nothing more than your iOS device. The app -- a universal binary -- works on the iPhone, iPod Touch, and iPad.
Upon launching the app you can connect your Facebook and Instagram accounts to it, or rely on photos stored in your Camera Roll to curate your short video.
You can place as many photos, or "Moments" as the app refers to them in your video. There's a quick toggle for ensuring the video is exactly Instagram length, otherwise known as 15 seconds. Or if you plan on sharing elsewhere, you can control the speed of the overall progression through your photos.
You can also add a title and select a font from a list that's far too long for a mobile app. A watermark will be placed on your video, unless you unlock the feature for a fee of $0.99. Doing so will allow you to remove the default watermark, or add your own. Again you can customize it using one of the included fonts.
And yes, there's also an option to add your own music to the slideshow. You're even able to select what part of the song the videos starts with.
Once you're done with the video you can save it to the app, Camera Roll, or upload it directly to Facebook and YouTube.
Overall Flipagram provides a nice user experience. You can view a video I made and uploaded to Instagram in under 5 minutes here.
Currently the app is listed as free in the App Store; the price was reduced last month. The app description states that this is a special price for a limited time. So even if you're on the fence about its usefulness, download it anyway. Who knows, you may end up loving it.