Treasure Hunter Storage.
This is an interesting storage key, as it hold SOS and TMaps, lock picks and shovels.
Perhaps require special TMaps and SOS to be discovered, from looting special theme based TMaps and SOS, that have a random chance to be inside the chest while doing a themed TMap. The chance for this would increase as the difficulty of the TMap increases. It would require the entire chest to be emptied, before it had a chance to appear. It would require the Special TMap from each level of Normal Themed TMap. The special SOS would only appear inside of the Pirate themed TMaps, instead of a Special TMap.
These special TMaps and SOS would be required as a turn in item, for the quest. Each special TMap and SOS would have a chance to drop another required item for a turn in.
This might be possible to create the locations for these in areas that do not currently have a TMAP system in place, such as Tokuno, Ilshnir, and Malas or areas of Tramel and Felucca that do not have TMaps associated with them. Areas such as Ice Island and areas between sections that have TMaps in the current system.
Which could be constructed as themed maps for that area, such as Malas being an undead or desert themes, Ilshnir as a dinosaur (no velociraptor from Jurasic Park) theme, and Tokuno could be anything from Serpentine Dragons, Hyru, Ki Riin, Sohi, Yamabushi, (no Samurai please), etc.
As for the special SOS, perhaps this would allow Kane to bring in creatures from the High Seas expansion to be used much like a dungeon boss, but it only has a chance to appear after all the other creatures are destroyed. Some recoding of the sea creatures would be necessary to prevent them from swimming away and becoming lost. Perhaps a leash mechanic, such that the creature is required to stay within a certain radius of the initial location of the Special SOS.
Hope this gives people other ideas, to hopefully give Domino and Kane even more ideas on things that can be done for the quests for storage keys.