Ya they definately need to make the puzzles use more than one item, or use an item in a way you havent before. or at least an item not from that dungeon.
What would be cool if you got an item, say iron boots, and went underwater, then used them as a weight to get acrss windy places or to...
An item that allows you to switch places with certain objects like statues or something.
A temperature device that allows you to increase the temperature or decrease the temperature of an entire room or of certain objects
A few new kinds of swords (two-handed would be nice to have again)
Magic...