You're gonna give away all my secrets!
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Shovel of Ponz (or any of the magician focus items) - reclaim your pet for mana; this can be a lifesaver if you run OOM, giving you enough for a few heals, or gate, or whatever.
Fang Amulet of Calling (Shaman only) - instantly summons a pet. Used in conjunction with reclaim energy, you can summon a pet and then instantly reclaim it for a little bit of free mana.
Reaper of the Dead - instant complete heal, usable from inventory, castable on others.
There's plenty more but those are some of my favorites, in addition to the WC cap.