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.
The Deep Strike is the Space Marine's iconic deployment method. A pod holds ten Marines, one Dreadnought, or one Thunderfire cannon with gunner. It takes a lot of the guesswork out of Deep Striking because it avoids obstacles automatically -- that's why Boreale loves them so much. For entirely unexplained reasons, once the pod lands, no one can stand (or sit) inside it again - everyone has to get out, and then some sort of miracle bars them from re-entry.
Deathstorm Drop Pod
A drop pod that holds 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 (they fire D3 times at every unit with 12" the turn they come in).
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 been 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 the dread can stay inside the pod, to use it as ablative hull points, and 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.
Found in IA2:2nd, these pods also have drop pod assault and can get precision deep strike for 20pts using Dropsite Massacre legacy rules in the appendix, but as drop pods they already had the ability to reduce scatter. Yes it still has the assault vehicle rule (despite already having it for being open toped - typical Forge World rules stupidity for you), but that still doesn't actually allow things to charge the turn they deep strike, very few things get around the BRB that way.
Kharybdis Assault Claw
A Super Heavy Drop Pod used during the Great Crusade, capable of carrying twenty Marines or a pair of Dreadnoughts. Also used for burning shit with its engines as it flies over it, and melting shit it lands on.
Dominica Pattern Drop Pod
The version used by the Sisters of Battle and inquisitorial strike forces, last seen in 2002. Only holds five people, the rest of the space probably being used with shock dampeners to make up for the occupants' lack of suprahuman physiology, or a votive shrine.
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, and even Marines themselves, even before the pods fell to Chaos, hence why the Dreadclaw wasn't very popular amongst legions, who actually gave a fuck about their mortal serfs. And then when the Heresy kicked off, the last thing Imperial Navy captains wanted was a bunch of murderous pods with heavy Melta guns right next to their bulkheads.
That said, for the Chaos Legions, they've become much more safe and docile.
Also, somehow, evidence suggests it's daemon proof. When daemons are too scared or can't even possess them, you know it's good.
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 defences.
In the Command & Conquer universe, by the era of Tiberian Sun, GDI makes use of drop pods, fired from their orbital space station Philadelphia as very quick response troops. The pods are rather small, holding only one trooper each, and have forward mounted machine guns which give off a nice hail of gunfire while dropping to at least somewhat clear the landing zone. While the soldiers come as Elite ranked, they are only otherwise regular Light Troopers and Disc Throwers (though the first mission's FMV depicts them having some kind of crazy Railgun/beam weapon). Was only available when mission triggers dropped them, but as of Firestorm, the Upgrade Center gave you the choice of building a plugin for a rechargeable targeted power, fuck yeah.
By the time of the 3rd Tiberium War , GDI is capable of dropping 3 squads worth of Zone Troopers, elite infantry specialized in operating in tiberium infested areas.
A Jokaero Drop Pod.
|Forces of the Sisters of Battle|
|Command:|| Canoness - Ecclesiarchy Battle Conclave |
Ministorum Priest - Sororitas Command Squad
|Troops:|| Avenging Angel - Arco-flagellant - Battle Sister Squad - Celestians |
Crusaders - Death Cult Assassin - Dominion Squad - Retributor Squad
Seraphim Squad - Sister Hospitaler - Sisters Repentia
|Vehicles:||Exorcist - Immolator - Penitent Engine - Repressor - Rhino|
|Flyers:||Avenger Strike Fighter - Drop Pod|
|Saints:||Living Saint - Geminae Superia|
|Forces of the Adeptus Custodes|
|Command:||Companions/Hetaeron - Shield-Captain|
|Troops:|| Aquilon Terminator - Custodian Guard |
Sagittarum Guard - Sentinel Guard
|Walkers:|| Contemptor-Galatus Dreadnought |
Telemon Heavy Dreadnought
Venerable Contemptor Dreadnought
|Vehicles:|| Caladius Grav-Tank - Coronus Grav Carrier |
Drop Pod - Grav-Rhino - Gyrfalcon Pattern Jetbike
Pallas Grav-Attack - Rhino - Venerable Land Raider
|Flyers:||Orion Gunship - Stormbird|
|Titans:||Warlord-Sinister Pattern Battle Psi-Titan|
|Auxiliaries:||Sisters of Silence|