Four japanese female manga artists:
Nanase Ohkawa (scenario)
Mikku Mekoi (design assistant)
Apapa Mokona (main artist)
Satsuki Igarashi (design assistant and more)

clamp clamp clamp clamp

CLAMP started by doing Doujinshi (fanart comics)
They do not limit their style to shoujo or shounen, kiddy or dark or any presets at all. Each series is different and appeals to very different types of readers.
They like to take risks, change around and try new techniques:
Clover was one of their experiments in design and narration
Mikku did most of the drawing for Wish
Chobits pushed controversy with a robot/human love story with ecchi hints.
They style is really quite particular, with special attention to details (like the clothing).
Their men have huge huge shoulders or have a thin soft feminine delicate look.
Their stories usually have an unusual level of sexual wierdness/difference (androgynes ; teacher-pupil relationships; angel/protegé relationships; and some shounen-ai + shoujo-ai -usually ambiguous enough to be debated by the fans-)
Not all stories have a happy end (I'm not telling which though ^_^)
They love crossovers and many of their characters appear in other mangas (not just the latest Tsubasa!)
There is a music video called CLAMP in wonderland which features characters from "old" series (MKR, CLAMP school detectives, X...)
They also appear themselves in their chibified forms in the Wish omake (see picture below)

Works? (Thankyou Kira and Sakura/Yiyi for sending in information)
Here is a list of some of the most popular clamp works
- CCSakura (12 manga - many illustration books -70 tv episodes - 2 movies - 3 OVAs - complete) a magical girl cute story
- Chobits (8 manga + 26 tv episodes - complete) does love between robots and humans exist. mild ecchi
- X (aka X/1999) tv + manga still being released - a spiritual dark story . some violence
- Angelic layer: tv+ manga cross between pokemon and barbies?
- Magic Knight Rayearth: tv + manga tokyo school girls save the world with mechas (Mokona the little bunny type character in MKR was named after Mokona Apapa)
- Tsubasa Reservoir Chronicle (aka wing) a crossover/new fantasy story
- Clover: A retired soldier must get Suu to fairy park but the way there is full of danger
- Wish: (angel + human love?)
- Man of Many Faces- short but sweet romance between a thief and an 8 year old girl ^_^;; (the thief is 10 so they're not too far apart) It lasts 2 volumes.
- CLAMP School Detectives- about these young kids who go to CLAMP school which is a very prestigious school for the best, smartest kids. They are detectives and are dedicated to making the school safe for the girls ^_^;; Also stars the main male from Man of Many Faces. 3 books.
- Shirahime-Syo: Snow Goddess Tales - Folk tales and legends about the snow princess, Shirahime-Syo. It's said that when Shirahime-Syo cries, it snows. 2 books.
- XXXHolic- The witch Yuuko can grant special wishes to people for a price. Watanuki Kimihiro desperately needs her help and so he's roped into working for her. One day they get some special visitors named Sakura and Syaoran from the Clow Country. Crosses over with Tsubasa: Reservoir Chronicle!
- Suki - about a girl named Hinata Asahi who lives alone except for her teddy bears. One day a cute guy moves next door and she's attracted to him. She soon learns he's her new teacher! They start to take interest in each other but he's not who he seems to be. He and a friend of his have been spying on their newest target, her!
- Lawful Drug is some guys who are ordinary pharmacists by day but at night, their boss has them creating drugs for 'special' ailments. Has cameos from Suki.


Where?clamp official website (in japanese) (italian) (japanese) (english)