Rocket Boots Xtreme

Source
Rocket Boots Xtreme are a rare leather foot item made by engineers with a minimum skill of 355.

drops from Mekgineer Steamrigger in the Steamvault. The drop rate appears to be about 0.8% for the normal instance, and somewhere between about 3 and 10% for the Heroic instance.

Rocketboots uses
The Rocket Boots Xtreme can be easily combined with items that give slowfall (such as the engineering Parachute Cloak) to be able to jump vast distances. Although the timer for the boots is rather short, any slowfall affect will continue your forward speed until you land. Using these mechanics together a player can use the Rocket Boots Xtreme to great effect. An example of the uses of this tactic is using the rocket boots and Parachute Cloak (or, other slowfall item) in Warsong Gulch. Players can cap the flag and then run towards the graveyard where the ledge is. Once there the player can jump over the entire battle to their own side in seconds.

As of patch 2.4, using the boots while carrying the flag will cause the flag to drop. Using the boots and then picking the flag back UP hasn't been confirmed to work, but might very well do so.

Rocket Boots Xtreme also deal a nominal amount of damage after the effect runs out, so using them at the proper time can be used as a CC breaker for an ability like Polymorph (instead of the more traditional "run real fast" idea).

Trivia
The buff you gain from using the boots (Rocket boots engaged!: Ludicrous Speed!) references a scene from the Star Wars parody Spaceballs.