The relevant "Designer's Notes" column in Pyramid Magazine had a Suspiciously Specific Denial concerning the non-existence of an expansion pack called BDSM: Barbarian Dogboy Space Marines...
Also from Steve Jackson Games, Munchkin's myriad and sundry genre-spanning sets can all be combined, with minimal rule modifications for doing so. Also present in some individual cards, such as "freezing explosive potion" or "flaming poison potion".
Recommended combo for a more or less literal Ninja Pirate Zombie Robot character: Star Munchkin, the new Munchkin Booty, Munchkin Fu, and these rules. For added hilarity, add any of the other sets. Or all. Example: Ninja Pirate Zombie Munchkin can be created using: Ninja (Munchkin Fu + Munchkin Impossible), Munchkin Booty, and Zombie Munchkin.
The Munchkin Blender pack is specifically designed to spice up set blending, and includes cards that allow a player to have a character with three races et cetera.
Z-Man Games has a series of B-Movie card games (all of which can be combined into, well . . .) which take every trope you can think of in a genre, and using it. Titles include Grave Robbers from Outer Space, Bell-Bottomed Badasses on the Mean Streets of Funk, Bushwhacking Varmints out of Sergio's Butte, and Kung-Fu Samurai on Giant Robot Island.
Magic: The Gathering's Mistform Ultimus is as of the M13 creature type Oracle update, in alphabetical order, an Advisor, Ally, Angel, Anteater, Antelope, Ape, Archer, Archon, Artificer, Assassin, Assembly-Worker, Atog, Aurochs, Avatar, Badger, Barbarian, Basilisk, Bat, Bear, Beast, Beeble, Berserker, Bird, Blinkmoth, Boar, Bringer, Brushwagg, Camarid, Camel, Caribou, Carrier, Cat, Centaur, Cephalid, Chimera, Citizen, Cleric, Cockatrice, Construct, Coward, Crab, Crocodile, Cyclops, Dauthi, Demon, Deserter, Devil, Djinn, Dragon, Drake, Dreadnought, Drone, Druid, Dryad, Dwarf, Efreet, Elder, Eldrazi, Elemental, Elephant, Elf, Elk, Eye, Faerie, Ferret, Fish, Flagbearer, Fox, Frog, Fungus, Gargoyle, Germ, Giant, Gnome, Goat, Goblin, Golem, Gorgon, Graveborn, Gremlin, Griffin, Hag, Harpy, Hellion, Hippo, Hippogriff, Homarid, Homunculus, Horror, Horse, Hound, Human, Hydra, Hyena, Illusion, Imp, Incarnation, Insect, Jellyfish, Juggernaut, Kavu, Kirin, Kithkin, Knight, Kobold, Kor, Kraken, Lammasu, Leech, Leviathan, Lhurgoyf, Licid, Lizard, Manticore, Masticore, Mercenary, Merfolk, Metathran, Minion, Minotaur, Monger, Mongoose, Monk, Moonfolk, Mutant, Myr, Mystic, Nautilus, Nephilim, Nightmare, Nightstalker, Ninja, Noggle, Nomad, Octopus, Ogre, Ooze, Orb, Orc, Orgg, Ouphe, Ox, Oyster, Pegasus, Pentavite, Pest, Phelddagrif, Phoenix, Pincher, Pirate, Plant, Praetor, Prism, Rabbit, Rat, Rebel, Reflection, Rhino, Rigger, Rogue, Salamander, Samurai, Sand, Saproling, Satyr, Scarecrow, Scorpion, Scout, Serf, Serpent, Shade, Shaman, Shapeshifter, Sheep, Siren, Skeleton, Slith, Sliver, Slug, Snake, Soldier, Soltari, Spawn, Specter, Spellshaper, Sphinx, Spider, Spike, Spirit, Splinter, Sponge, Squid, Squirrel, Starfish, Surrakar, Survivor, Tetravite, Thalakos, Thopter, Thrull, Treefolk, Triskelavite, Troll, Turtle, Unicorn, Vampire, Vedalken, Viashino, Volver, Wall, Warrior, Weird, Werewolf, Whale, Wizard, Wolf, Wolverine, Wombat, Worm, Wraith, Wurm, Yeti, Zombie, and Zubera. * phew* The list was a lot longer before the Grand Creature Type update. It is a Ninja Pirate Zombie, but, unfortunately, not a Robot. It is a Construct, though. It's also a Mutant Ninja Turtle.
See also this comic◊ for several other things it is. Unfortunately, with the GCTU, all of these except "Fish Monger" no longer apply.
The Mistform Ultimus has somewhat lost its unique status with the Lorwyn block and its introduction of the 'Changelings', shapeshifters with an eponymous ability that grants them every creature type at all times. Amusingly enough, there are also some 'tribal' cards with that ability that aren't themselves creatures at all — Wings of Velis Vel, for example, is an Advisor-Angel-Anteater-Antelope-...-Wurm-Yeti-Zombie-Zubera spell that temporarily sets a target creature's power and toughness to fixed values and grants it flying and all creature types in turn for the duration too.
Apart from the special case of changelings, there are many completely intentional interesting combinations of creature types; recent ones include Minotaur Wizard, Human Ooze, Zombie Plant (and a whole lot of other Zombie combinations).
Ninja Burger, which combines Ninjas with fast food delivery.
The premise of the card game Smash Up, where each player is required to make a deck by combining two unrelated factions. In the base game, the expected Ninjas, Pirates, Zombies and Robots are joined by Aliens, Dinosaurs, Wizards and "Tricksters" (i.e. The Fair Folk).