These are cartoons intended specifically for adults and they all run 15 minutes. Why they don't make them longer, I don't know. My personal favorites are
Metalocalypse,
Squidbillies, and
Morel Orel. If you want to watch more, check out
adultswim.com. They post each weeks episodes online for free. Also, if you've seen
Aqua Teen Hunger Force and like it, they have like two DVD sets out. Hope that helped you out some.