Blood? Contractors? Mysterious green haired women in white suits? Pizza Hut everywhere? Same time slot?! That's right - Darker than Black and Code Geass have all these qualites in common. If you like one, there's a good chance you'll find the other good/funny.
Pizza Hut logos all over the place, contracts formed with mysterious entities, and green haired women. Anyone who's watched Darker than Black will feel right at home with Code Geass (or vice-versa). Both series feature societies in the future, oppression from a government/external power, and protagonists that attempt to change the world they live in. Oh, and both protagonists are very close to their sisters who are basically their reason for living.
Darker than Black and Code Geass are both in a technological world where the protagonist have a very powerful ability. There are lots of pizza hut hidden in the background or just somewhere on the screen. Suspense and fights, thats what they are all about.