What do you do with the key on Poptropica?

There are keys on several islands on Poptropica :

• Shark Tooth Island : the "translation key" is a page from Professor Hammerhead's Journal. The "key ingredient" is for the shark potion.
• Big Nate Island : if you recover his lost lobster trap, Cap'n Salty will give you the key to his jet ski.
• Astro Knights Island : the small key opens Mordred's underground lab. The Golden Key opens the path to Mordred's hideout with the portal on the crystal asteroid.
• Counterfeit island : the key opens the Inspector's house in the Country Side.
• Steamworks Island : each of the three coded keys allows you to open a door using the Steam Battery.