Those are all cartoons geared towards adults, except Robot Chicken, which is claymation.
Squidbillies is redneck squids in a deeply dysfunctional redneck town.
Aquateen Hungerforce is a milkshake, french fries, and a blob of meat who have various adventures, such as being evicted, bagaining with their landlord who is some sort of demon.
Harvey Birdman is a superhero who chooses to practice law instead.
Sealab 2021 is a re-make of the 70's show Sealab 2020, except with ne're do wells and morons running the lab.
Robot Chicken is various short vignettes featuring dolls and claymation. It's voiced by Seth Green and frequently has big name guest voices. Green is more popularly known as Scott Evil from Austin Powers. The Robot Chicken Star Wars is definitely a goodie. He shares the same fascination Seth McFarlane has with the movie and there are occasional cross-over references.
Metalocalypse is a cartoon about a heavy metal band. Dethklok wears pelvic thrust mace belts to protect themselves from rabid fans.
Other shows on Adult Swim include Boondocks, Family Guy, American Dad, Space Ghost Coast to Coast, and Lucy, Daughter of the Devil.
Those are the only ones I recommend. There's also endless manga and some truly awful crap like the Tim and Eric Awesome Show, Tom Goes to the Mayor, and Saul of the Molemen.
You can see videos online
http://www.adultswim.com/