Non-uniform content-aware image resizing
Ever wanted to resize or crop a photo without losing essential details or having weird artifacts due to a changed aspect-ratio? Check this out:
http://www.youtube.com/watch?v=vIFCV2spKtg
I can imagine lots of applications for this, both good (remove your ex from that awesome group shot from a few years back) and evil (alter photographic evidence being presented at a trial). I guess an interesting but probably much harder next step would be to use similar algorithms to transform a video stream.