Currently running in Shonen Magazine in Japan is CLAMP's latest manga, Tsubasa: Reservoir Chronicle. "Tsubasa" is Japanese for wing or wings.

Sakura, the princess of Clow Country, has a vision of a mysterious object. The next day, she visits her childhood friend Syaoran at the excavation site he's working at. She sees the mysterious object - and begins to get pulled in to it! Wings appear on her back. Syaoran manages to pull her back, and her wings disappear - but Sakura is unconscious, and the palace magician Yukito says that the wings were Sakura's memories. Now that they're gone, Sakura will die! And so Yukito sends Syaoran on a quest to find the feathers of Sakura's memories, which have been scatted throughout different dimensions. Joining him on his quest are Fye, a magician who left his dimension to escape an evil king; Kurogane, a swordsman who was banished from his world by Princess Tomoyo; and Mokona, a magical creature given to them by the Witch of the dimension.

Tsubasa is made up of a lot of crossovers. Sakura, Syaoran, Yukito, Touya, Fujitaka, and Tomoyo from Card Captor Sakura appear; Chii from Chobits is in it for a few pages; Mokona from Magic Knights Rayearth; Ashura and Souma from RG Veda; Sorata and Arashi from X; possibly the Dash card as well.

Plot summary taken from my CLAMP website, http://www.geocities.com/wish_kohaku01/