In the U.S. so far there are 10 published, the 11th volume comes out in November of 2008. I have read 10.
The series is so random, basically. Most of the characters are kind of clueless. Tamaki thinks of himself as a "father" to Haruhi. Haruhi is in the Host Club's debt because she accidentally broke an 80 million yen vase that the Host Club was going to auction. The Host Club has 6 members, disincluding Haruhi and Renge, who, in the anime, is supposedly the manager. Tamaki, the leader, "King", "Lord", "pervert", is unaware of his love for Haruhi. No, he is aware, it's just he thinks he's her father, and he doesn't know he's IN love with her. Kyoya, or Kyouya, is known as the "demon lord no.1" (no. 2="bossa nova", no. 2=Haruhi). When he's tired he's grumpy, he comes from a famous-ish rich family (all the students are rich at that school except for Haruhi, who is there on a scholarship), basically knows everyone's background, is very secretive, and loves it when people owe him money. Haruhi is a commoner at a rich school and is there on a scholarship. She is somewhat clueless of her own feelings. Kaoru and Hikaru are twins, they share everything there isn't 2 of, they used to hate everyone but themselves, and they don't spend much time with their parents, and their mom is a designer. Hunny, or Honey, is the oldest, or second oldest, it is said that Hatori made a mistake in the manga, and the shortest. One of the wisest, actually. He's extremely short for his age, and is like a little kid, he loves cake and bunnies and when he's sleepy he's angry. There are said to be legends about him in the book. And he used to be captain of the karate club, I believe. He has a little brother, Yasuchika. Takashi, known as Mori, is a quiet, expresionless 3rd year with a fetish for small things. Hunny for example, is his cousin and best friend. He takes care of him basically. Not much is known about him, but he does like a certain fish that I forget what it's called (according to the manga)In the manga, he has a little brother, Satoshi, who is the same age as Yasuchika (the Morinozuka family (Mori's family) serves the Hanninozuka family (Hunny's family)). Renge is...Renge. She is....otaku, according to the Host Club when she first showed up in the manga. She loved Kyoya because he looks like a character from a game. No one but the Host Club (disincluding Renge) knows Haruhi is a girl. She can't pay off her debt unless they think she's a boy. Renge starts to like her instead of Kyoya (because she thinks she's a boy). According to Tamaki, Haru-chan is a "natural host".