Hmmm...
Heward's Handy Haversack
Rings of Protection +*
Cloak/Vest of Resistance +*
Wand of Cure Light Wounds
Flying Carpet
Slippers of Spider Climb
(Or, a way to carry things easily, a way to protect yourself, a way to heal, and a way to travel.)
In a high-level game I found the Iron Fortress - the little box you set down and say a phrase, turning it into a protected tower - to be tons of useful fun, both as simple domicile, and also as an occasional weapon/battlefield control. But it's really expensive and, well as I said, high level play.