Engineering is a profession. It's sometimes entertaining, sometimes funny, sometimes useful, sometimes useless and sometimes the biggest waste of gold you'll find in game. Of the crafting professions I've leveled to 450 - currently Leather Working, Jewel Crafting, Enchanting and Engineering - Engineering was by far the most expensive and painful. For every one useful item you are able to craft, you'll make three useless ones.

Engineering is not a profession that you should pick up if you are strictly looking to make gold. From my perspective I've only really found a handful of ways to make money from engineering. The first is making ammunition to sell on the Auction House - although with Blizzard removing ammo from the game come Cataclysm my days of selling ammo for gold are fast drawing to a close. The second is selling scopes (eg. [Heartseeker Scope]), although depending on demand and your server the profit margin on these may not be worth it. Finally, engineering allows you to use the [Zapthrottle Mote Extractor] which lets you collect crystallized elements or mote from various clouds in Northrend and Outland. Selling these on the Auction House is always a decent source of gold.

Engineering should be the profession of choice though if you want to make some fun and occasionally useful and/or life saving objects. Here are some of the reasons why you should consider taking up engineering.

• Once you become a Grand Master engineer you are able to access the Auction House from Dalaran. This is a major convenience - particularly if Dalaran is your home - and can really cut down on travel time and getting stuck in the old world if your hearth is on cool down.
• [Jeeves] - Once your engineering skill hits 450 Jeeves is one of the first things you should look to build. This little guy can be summoned by engineers and can be used by anyone in your group to buy, sell and repair. As an added bonus, Jeeves also allows the engineer that summoned him access to their bank.
• [Gnomish Army Knife] - "A grand master engineer can overload the knife's battery to attempt to shock a dead player back to life. Cannot be used in combat. (30 Min Cooldown)". If you are a rogue, hunter or any other class that can somehow disappear from combat when a wipe is inevitable, having one of these in your backpack can be a nice little wipe recovery tool. The resurrection function is not always successful, but when it works, it's oh-so-sweet.
• [MOLL-E] - Summon a mail box where ever you are. MOLL-E can be used to send and receive mail by anyone of the same faction regardless of whether you're grouped with them or not. If you're out farming you can always use MOLL-E to empty your bags and send stuff to an alt or bank mule.
• [Mekgineer's Chopper] - Arguably the coolest ground mount in the game. Very expensive to make. The Horde equivalent is the [Mechano-hog].
• [Wormhole Generator: Northrend] - There are a few other wormhole generators that you can make, but the Northrend one is my personal favorite. Use it to open a port to various places around Northrend. Just make sure you have a parachute or flying mount though because you don't always end up in a 'pedestrian friendly' area.
• [Flexweave Underlay] - "Permanently attaches a flexweave underlay to a cloak, increasing Agility by 23 and allowing you to turn the cloak into a parachute to fall slowly for 30 sec." A must have enchant for anyone using the Wormhole Generator without a flying mount.
• [Zapthrottle Mote Extractor] - A must have engineering tool that lets you extract crystallized elements or mote from various clouds in Northrend and Outland.
• [Explosive Sheep] - Ok, so summoning an explosive sheep that will charge at nearby enemies and explode isn't the most useful, but it is quite funny. The sheep only does 135 to 165 damage so don't expect it help you charge up the 'Recount' ladder.

So there you have it. My list of reasons why I like engineering. You can pretty much file all of them under the same two categories, fun and convenience. So if fun and convenience are your bag, then engineering may just be for you.