Theiving weapon? Possibly worth picking up a below level one -- lets you steal in combat as a daily power (when you hit with it, but still).
Deep Pocket Cloak -- sure, uses your neck slot -- but a Bag of Holding and Fast Hands in one handy item!
Look over the consumable and wonderous items -- there are lots of gems there, particularly if you're going with a "bag of gadgets" approach. Nail of sealing, Heartflow, Smokestick for consumables; eternal chalk, Window of Escape (if your GM doesn't disallow it), Floating Lantern, etc.