ClowCardD-E

The Dark Card, sister of the Light Card. Appeared in the infamous Sleeping Beauty episode and in manga volume 5. It is one of the two most powerful cards.

(It casted the whole auditorium into darkness in the middle of the play. Much to the disappointment of the viewers, it was getting to the good part when it happened.)

This card is a Special card (I think, don't take my word on it), meaning that if you find the identity of this card and call out its name, it will lose its power and thus enabling it to be captured. But for this card, it wasn't enough. I can say no more for fear of giving spoilers.

The Dash Card, what a cute lil' thing! Appearing in anime only, this one showed up in Episode ___ (forgot, remind me to look it up). It's a very fast card, but can only sprint over a short distance. Basically, it has the power to make living things faster.

In this episode, Sakura is relunctant to capture this card because it got taken in as a pet by a schoolmate of Sakura's. It was her "good luck charm", and she loved it. What's even cuter, she named it Pee-Wee!

Another Notable: The dubbed version of this episode is actually decent! Not great, but not as terribly unnerving as the other episodes.

The Earthy Card. *insert dramatic music here*

Yes, the Earthy card is that important. Even if I don't have the picture. It was captured in manga volume 6 and Japanese episode ___(I'm losing it, I can't remember the episode numbers)

Jess, Selphie: *koff*youalreadylostitalongtimeago*koff*

HB (ignoring fellow colleagues and continued):
This Card is an element card. Kind of self-explanatory, it's one of the 4 elements (Wind, Water, Fire, Earth) and one of the most powerful cards. It uses the power of Earth (also self-explanatory). It is pretty destructive, nearly took out the temple before the Card Captoring "team" caught it.

Spoilers (highlight to read):

The Fire and the Earth cards give Cereberus his powers. Without them, Cerberus is just a lil' tiny stuffed "doll" (as referred to by many) named Kero-chan. Also, when Sakura captured all 4 element cards (the last being the Earthy), Kero-chan returns to his true form, the fearsome Guardian of the Seal. Yeah, the one that Syaoran had in his mind when he first heard about him. But it is still cuddly (not in his, but everybody else's opinion), and still referred to as "Kero-chan" from the girls (much to his dismay).

The Erase Card. Shown in an unbelivably cute beach episode in the anime (epi. 17), and an equally cute manga episode (vol. 4). It can make people disappear! Which is very scary when you're in the middle of a dark cave testing your courage.

Notables: This is when we find out about some of Syaoran's past that Sakura's been puzzling over for a long time, and we also see them working together (sugoi!) and competing (double sugoi). One of those competitions was a fight for Yukito's love. (Shonen-ai moment. Jess was very disturbed by it. Not so surprisenly, I wasn't ^^)