I think advertisement is driving the whole photo manipulation thing and here are some truly amazing pieces how much you can accomplish manipulating photos.
40 Incredible Photo Manipulations in Advertisements
Público Newspaper 1000 objects of design: Nikon
Foorire FM Radio Comedy Station: Arthur M'bidonné
TMB (Transports Metropolitans de Barcelona): Shark
Yamaha: Octopus
Steel TV: Into Action, Rapunzel
Disney's Hollywood Studios: Grievous
Studio Brussel: Nevermind '91
3M Photographic Paper: Loch Ness monster
Indian Premier League 2010: Warne
LG Air Conditioners: Teen Couple
City FM classic rock: Gene
Claro TV: Spiderman
Claro TV: Hulk
Pastorini Toy Store: Conductor
Hasbro Upwords: Cat
Fenistil Gel: Burn
Calgary Zoo: Caveboy
Hipoglós Amêndoas: Dream
Future Brands: A brave new world
BGD Stray Animals Foundation: Count
Sitges Sci-fi & fantasy festival: Octopus
VOG SOCKS: BLUE
Tervolina Shoes & Accessories: Imperfect world
Westcoast International Dental Clinic: Lolly pop
Chronic’art Magazine: Zombie
Sundek Surfwear: Avatar Girl
HARVEY NICHOLS: WOLVES
Burjuman
ROLLING STONE: BABY
Rig Net
SETE LEGUAS BOOTS: OLD LADY
Milk
Henkel Dixan Gel: Predator Ink
Veikkaus Football Betting: Meercat
Gorilla
Hawaiian Tropic: Pool
Bosch
Abdul Skateboarding: Halfpipe
Nike Football: Write the Future, Ronaldo