One thing I love about content patches is someone creative at Blizzard always sneaks in a few fun toys. Here's two I've been enjoying using.
Jewelcrafted focusing lenses like the Shadow Jade Focusing Lens. When you use one you channel a spell that draws a beam%26#0160; of light between you and your target. Has a fairly long range, about 60 yards. They look cool, but they're actually useful too. See, the beam ignores line of sight. Ever had something targeted and you couldn't find where it was, like an NPC in the godawful town of Booty Bay? Just /target them and use the lens and now you have a beam pointing the way. I also imagine it'll be useful in PvP to point out targets. The only drawback is you can't move while channelling the beam.
The Toy Train Set from the toy vendor in Dalaran. Best 250g I ever spent. You put it on the floor and everyone within 5 yards starts doing the /train emote. Whether they want to or not. It's like the Piccolo, only noisier and more irritating. It's tempting to use this on a tight pack of people, say at the Naxxramas summoning stone. But that's unsubtle and awfully obnoxious. I've enjoyed placing it in unexpected places, like the spot where you arrive right when you zone into an instance or where you land from a flight master. Putting it under a repair bot was pretty funny, too. Definitely needs to be used sparingly: I fear my guild might boot me entirely if I drop it in a raid again. (Guys, I love ya, I only used it last night to break the tension after our fifth wipe. Promise.)