Here's mine:
For the "realistic" version:
-isolated girl (so cute, btw) inserted sky w/bubbles background in Photoshop CS2
-adjusted exposure in the "image-adjust" settings (lowering the gamma slider made a nice difference)
-tiny adjustment of shadows/highlights
-upped contrast by 5
-lowered saturation of girl layer a little bit
-sharpened using "Smart Sharpen"
-did a tiny curves adjustment
That's it.
For the "fun" version, I was trying out this tutorial (didn't do all of the steps at the end though):
Make Your Images Look Awesome with a Few Light Effects