Drop Pod
Just about every modern sci-fi setting has a military that uses Drop Pods to deploy; if you take a sufficiently broad interpretation, you could say that the Martian cylinders from H. G. Wells' The War of the Worlds were the very first drop pods, but it was Robert Heinlein's Starship Troopers that really crystallized the concept as we know it: a means of deployment for super-elite soldiers right where they are needed, when they are needed, and in style.
Warhammer 40,000
The Deep Strike is the Space Marine's iconic deployment method. A pod holds ten (or twelve, if you're a Codex Astartes-compliant chapter) Marines, or one Dreadnought, or one Thunderfire cannon. It takes a lot of the guesswork out of Deep Striking because it avoids obstacles automatically -- that's why Boreale loves them so much.
Deathstorm Drop Pod
A drop pod can hold weapons instead of soldiers. If a drop zone is just too hot to land in, the Space Marines will use Deathstorm Drop Pods (equipped with assault cannons or Whirlwind missile launchers) to clear the way. They're only BS 2, but they compensate through volume of fire.
It would be a heartening sight if the Navy were to use these en-mass to support the Guard. Come to think of it, a massive volley of these things would be highly effective against Orks, Tyranids, and possibly Necrons. They could also be useful as a rapid, highly potent response to daemons. After all, the fluff says fighting daemonic hosts is very difficult because they can poof anywhere on the battlefield, so there are no real battle-lines in such an engagement. In that vein, they may be useful against Eldar of all types, too. Hell, just shoot huge numbers of them at anything that looks at you wrong.
Lucius Pattern Dreadnought Drop Pod
A drop pod with all the restraints and harnesses taken out, and only three fins instead of five. This means that only a Dreadnought can survive landing in it. Previously, it allowed it to assault as soon as it land land, but now, when nothing can assault from reserves Lucius DP have being changed to granting Shrouded for himself, and everything hiding behind it or on it on the turn it deep strikes, likely to represent cloud of dust, dirt and debris, raised by its meteoric descent. Oh, and dread can stay inside the pod, to use it as an ablative hull points, end even fire his weapons from the inside, as it's open-topped. All in all a great way to deep strike your dread, and be sure he won't be shot off board the turn it drops.
Kharybdis Assault Claw
A Super Heavy Drop Pod used during the Great Crusade, capable of carrying thirty Marines or a full Dreadnought Talon.
Dreadclaw Assault Pod
The Imperium used to use the Dreadclaw, until they learned that its design made it receptive to the influence of Chaos during the Horus Heresy. This was not a problem for Chaos Space Marines, who use them to this day. Unfortunately, they are both more versatile and more deadly than drop pods; capable of being used as assault boats or drop pods and then return to orbit to get more marines. They also have plasma cannons to blast everyone with. Its machine spirit had been described as being unusually blood thirsty, which often caused lethal "incidents" with maintenance crews, even before the pods fell to Chaos, hence why Dreadclaw wasn't very popular amongst legions, who actually gave a fuck about their mortal serfs.
Forge World used to make these in Battlefleet Gothic scale.
Starship Troopers
Each member of the Mobile Infantry gets his own pod, containing his suit of armor. The armor is actually perfectly capable of surviving re-entry, and can even fly ("a little," as Heinlein writes); the pod is actually meant to disintegrate in the atmosphere, giving the Mobile Infantryman a cloud of chaff to confuse ground defenses.