I’ve seen all sorts of gear for Engineers in wow, and its great. Check your mail with the portable letterbox, teleport around with the trinkets, control your enemies with the mind control hats, and make useful bombs.
What I would really like to add is a Portable Anvil and Forge. Anytime (on a 1-3 hr cooldown perhaps) you can pop the item and have access to an Anvil and Forge to knock together whatever gear you need.
Oh, and more teleporters. Being able to jump around the world is so wonderful.