This series has become extremely popular recently, but I was a member of the CCSML almost right from the start!  I know a lot about this series, both anime and manga.  The manga is done by CLAMP (Rayearth, X, Wish, etc, etc, etc), whose artwork is absolutely gorgeous!  The rights for english versions of both the anime and manga have been purchased (blech!)  I will explain why I am upset about this later.

    Ten year old Kinomoto Sakura loves sports, hates math, and wants to grow really tall so she can step on her big brother Touya.  Sakura and Touya's mother died a long time ago, but their father is really nice and raised them well by himself.  Sakura always rollerblades to school following Touya on his bike so that she can see......her brother's best friend Yukito.  Sakura has a big crush on Yukito, who is like seven years older than her.  One day, Sakura finds an old book in her father's library.  The book is called the CLOW and when she opens it she sees a card called WINDY.  When she picks up the WINDY card, a whole bunch of other cards fly out and scatter all over Tokyo.  Then a cute little creature comes out of the CLOW.  His name is Kerberos (meaning Cereberus, from Greek mythology) and he is the guardian beast of the CLOW.  Unfortunately he fell asleep, so the cards escaped.  Kero-chan (his new nickname) explains to Sakura that she must become a Card Captor and catch all of the escaped CLOW CARDS.  He gives her a key, which transforms into a staff with magic, and now she can use the cards she catches (she only has WINDY to start with though).  Pretty quickly, Sakura's best friend Tomoyo finds out about Kero-chan and the CLOW CARDS and she helps Sakura catch them.  Tomoyo is very very rich and provides Sakura with a different costume for every adventure and she also videotapes it all.  Then a Chinese boy named Shaolan (it's actually Xiao Lang, but that doesn't work in Japanese) comes to try and take the CLOW CARDS.  I don't want to give anymore of the story away!

    My opinion on the pairings:  (SPOILER WARNING!) Tomoyo is in love with Sakura, it is clearly stated in the manga.  But she also knows that Sakura would not be happy with her, and she wants Sakura to be happy more that she wants Sakura to be with her.  She's very selfless in that.  So she helps Shaolan try to get together with Sakura.  It also comes out later that Sakura isn't really attracted to Yukito romantically, but he reminds her of her father.  In my opinion, Shaolan's supposed "crush" on Yukito was totally mistaken.  He was just reacting because Yukito was the first person to really be nice to him for no reason.  So after all of that, I think the final couples will be Touya and Yukito (come ON, they are soooo sweet, besides it's practically been admitted outright in the manga) and Shaolan and Sakura. I will put translations of scenes that are important, and evidence to support the relationships stated above (especially Toya and Yuki!)

Sakura and Shaoran!

Touya and Yukito!

The above images came from:  Kara's CCSakura Scans