How to create a soft vintage look with an iPhone picture?

http://instagram.com/...m/maldemar
This Instagram account has such beatiful soft vintage filter to all of its pictures and somehow it all flows and looks the same.
How do I create this look?
Is there a good app you know of? And if you know, what filter?

"somehow it all flows and looks the same. "- what you are describing is called "low contrast"

All you need to do is use an image editor. Reduce the contrast a little, and perhaps bump up the brightness a touch, and perhaps reduce the colour saturation a little. Almost any decent photo editing app for a phone can do it, or even image editing software for computers.

You will be better off editing your images on a computer instead of the phone. The main reason is that apps for the phone often overwrite the original file which means you can't go back and re-edit your work. Plus, putting the photos onto a computer gives you the opportunity to back things up just in case you loose your phone, it gets stolen, or breaks.

Try Vintagio app