Light Leaks normally occur due to low quality or damaged sealing in a camera so that stray light can come in and expose the film in unwanted ways. It shows up as a colored glare or discoloration in the image.
When trying to achieve a low-fi look for pictures I sometimes try to create an artificial light leak in post-production, like these:
I'm aware of a number of techniques to achieve this, mostly relying on either overlaying the picture with images of real light-leaks, using gradients or brushes with blend modes. All of those however need a lot of work per individual picture to look good and even then don't look as real (at least in my tries) as in the pictures posted above.
However there seems to be a technique being used with good results in applications like Hipstamatic in a completely automated fashion. Is anybody aware of a similar technique that consistently produces good and natural results for the majority of pictures you apply it on?