Well, DP hasn't so many places you can explore, finding rare items along the way. In fact, most of the time, you'll end up finding a mere Ultra Ball. But I did find something:

You know those empty houses you sometimes come across? I remembered stepping into one before and getting some item from a lady that was in, who was gone the next time I entered that house another day. Well, today (Friday, at ca. 10:20 AM), I stepped into the house on Iron Island, and (Spoiler:) Byron was there and after a little rant about his tough relationship with his son, gave me a Metal Coat before leaving!
So, if anyone knows the hour/day that someone appears in the other houses, could he fill me in?
The empty houses I know of are:
  • the one on Iron Island
  • the one in Canalave City, above the Sailor's house
  • the one on route 217, the other one being where you get some HM or Plate
Apart from those, I've found two things bugging me, and I'd like to know if they do something special:
  • The thirsty officer in the road house of Canalave City. Could just be a nostalgic flashback to RBY / FRLG, but has anyone succesfully offered him anything to drink? I always have Lemonade on me, but maybe this guy's more of a Moomoo Milk-type person...
  • The Psyduck in Snowpoint City's Pokémon Center: what's up with him? I tried the Secretpotion, but to no avail. Maybe it's just there to give me a migraine...
  • The cave in Celestic Town: any chance of anything appearing there when you come to it with the 3 Psychics in any order, or your coverbox Legendary, or Giratina for that matter?