I read an article somewhere online about an octopus at a giant outdoor aquarium (probably a Seaworld) that used to follow around the diver who was cleaning his tank. He was a large octopus, and the diver found this a little creepy. Every day the diver would go in, gather up debris into one spot, and when it was all gathered, put the debris in a sack and remove it, the octopus following him every "step" of the way. After about a month of this, the diver entered the tank-and discovered that the octopus had already gathered all the debris which would normally be gathered, and placed it all in the spot where it was normally placed for removal! After that, the octopus always had the debris ready for the diver, and a 30 minute cleaning job had been reduced to less than 3. I wish I had the link to the original story for you.
Ha! That's great! (The octopus was probably...bored!)