The following has various item ideas without much organization.
Amulet of Yurth
Legend says it will give a hero the ability to free the land from an oppresive ruler. Purpose of the game is to find this.
A powerful weapon to replace the sword. Possible allow chopping down trees.
Pick/Shovel/Gautlets of Digging
Allows travel through certain sections.
Already repels undead but the light effect it supposed to have isn't implemented. Until a decission of how to implement darkness is made this will likely remain.
Summonds the Phoenix which allows entry into the air palace and labyrinth. The character places the egg in the nest at the designated locations to summon the Pheonix. James Taintor original suggested the nest as where you could use it. He also suggested having the egg disappear after use and have it reborn in the volcano, however, that requires some method of leaving the dungeons with the egg. Another possible use of the egg could be fast transport around the surface world but that is unlikely.
Spider Magic/Web Magic
Stops monsters in a web. Maybe pick up items as well.
Crossbow & Rope
Allows the crossing water/holes in some areas.
Dust of Time
(Don't know what it does.)
Wand of Wonder
Produces random magic effects some good some not.