First was Sergeant Keroro. It's about an alien invasion -- only, the aliens are small and frog-like. A young boy who is obsessed with occult and weird things like ghosts and aliens and his sister accidentally discover Sergeant Keroro. Keroro is an alien, the commander of an alien invasion force!
The kids subdue him and take his Keroro Ball (a multi-function weapon of some sorts) from him. The boy experiments with it, and accidentally presses an emergency transmission button -- thus prompting the invasion force to retreat, leaving Keroro and his squad behind. Keroro is now forced to become friends with the people he would enslave, leading up to all sorts of wacky situations.
It's fun, but a bit too slapsticky for my tastes. The animation budget isn't very high either: the style is certainly cartoonish. Lots of physical jokes (usually involving the girl punching either Keroro or the boy).
Next was Samurai Champloo. This is a hiphop samurai series, so to speak. I think it is set in the period following the end of the Tokugawa Shogunate. Main characters are two ronin samurai: one cool and collected, the other one simple and living by his instincts. They get into trouble with the local prefect after his son is killed in a fire in the restaurant where the two have a fight. The serving girl from the restaurant saves their skins and 'hires' them to find 'a samurai who smells of sunflowers'...
The style is really something! Character designs are beautiful, fight scenes are beautifullt choreographed and animated, set to electronics music reminiscent of some of the fight scenes from The Matrix. Sometimes, we hear scratching (as in: the DJ technique), and the animation is fast-forwarded or rewinded to some different spot in the storyline.
It's an interesting mix of history and modern music and techniques -- one to watch!