Don't have Photoshop at this point (something I hope to correct sooner, rather than later), but iPhoto has a few tools I've been playing with as well, and did a couple of my own.
They have some effects that are nice pre-sets for the levels on the pictures.
A couple I've used are Antiquing, Color Fading, and Vignette - Sepia tone is a choice as well, but I wanted to try keeping a bit of color in the pic, and just fading the heck out of it.
Here's a couple of examples:
Scarecrow:


Witch with floating candles:

Not quite the same effect you've produced, but thought you'd like to see a variation.