Alchemist
Broken Glass - Resets the cooldown on Concoct
Potion - You can't get bad effects from Potions
Crystal Meth - You can easily get drinks as you can brew them
Grenade - Holy Hand Grenade
Bow and Arrows - Poison / Flaming
Assassin
Hammer - Assassinate
Sword - Assassinate
Lightsaber - Assassinate
Barbarian
Hammer - Leap
Sword - Leap
Lightsaber - Leap
Space Capacitor - Roar
Space Fluctuator - Roar
Illusionist
Hammer - Grand Disappearance
Sword - Grand Disappearance
Lightsaber - Grand Disappearance
TNT - Grand Disappearance
Glue Mine - Grand Disappearance
Grenades - Grand Disappearance
Lawyer
Gun - Useful for duels, either you get 10 of their rupees or you win and they die. Win-win. Even better, try to get life insurance and then do this.
Not an item, but Russian Roulette is useful for the same purpose.
Merchant
Light Wand: Cards of Fate - SHOPS
Wild Card - SHOPS
Necromancer
TNT - Gets you soul power
Phaser - Gets you soul power
Tome of Magic - Gets you soul power
Gun - Gets you soul power
Grenades - Gets you soul power
Paladin
Lasso - Sets up Holy Hammer
Space Capacitor - Sets up Holy Hammer
Space Fluctuator - Sets up Holy Hammer
Tractor Beam Generator - Sets up Holy Hammer
Banana - +2 spaces, good for Holy Hammer, also can be combined with Condom for +10, anything with set spaces is good for Holy Hammer setup
Pogo Stick - Sets up Holy Hammer
Priest
Light Wand: Revive - For when your Resurrect is on cooldown.
Anhk of Resurrection - To ensure you can always resurrect your teammate.
Saboteur
None of note, this class kinda sucks anyways
Sorcerer
Light Wand: Cards of Fate - Get a Bomb, cast Pyroblast and then throw bomb at them
Time-travel Condom - Sorcerer can steal a banana from Tarzan in the Pawn shop, then use this to go forward 10
Succubus
Hammer - Seduction
Sword - Seduction
Lightsaber - Seduction
Teleporter - Seduction
Explosive Sheep - - Seduction, place Sheep, roll, blow sheep.