Sun-ken Rock

Author(s): Boichi

Status(s): Ongoing

Reviews: It has action and romance. It's slightly mature but not like sexually (some parts are there). The story of hiding identities once more.

Mahou Sensei Negima!

Author(s): Akamatsu Ken

Status(s): Completed

Reviews: Prequel of UQ Holder. One of the BEST ACTION MANGA.

King of Hell

Author(s): Ra In-Soo

Status(s): Ongoing

Reviews: Plain old action. Gets a bit messy in the middle but still considerably good. Not much romance.

Accel World

Author(s): Kawahara Reki

Status(s): Completed

Reviews: For those who don't know it, one of the chapters here is Kirito vs Haruyuki. PLUS SEASON 2 IS COMING OUT!!!!

Sword Art Online

Author(s): KAWAHARA Reki

Status(s): Completed

Reviews: Just added this to tell those who don't know it that Sword Art Online Movie is coming out!!!!!!!

Magudala de Nemure

Author(s): HASEKURA Isuna

Status(s): Ongoing

Reviews: From the author of Spice and Wolf and is slowly being updated. Not quite action.

Rolan the Forgotten King

Author(s): YOSHINO Takumi

Status(s): Ongoing

Reviews: Made from the author of Rain. What more can be said? Although it does confuse me how it was listed as both shounen and shoujo in another site.

Kara no Kyoukai: The Garden of Sinners

Author(s): NASU Kinoko

Status(s): Ongoing

Reviews: By the makers of Fate/Stay Night. The anime version of Tsukihime. There isn't as much romance as Tsuikihime (don't watch the anime version) but good.

Yu Yu Hakusho

Author(s): TOGASHI Yoshihiro

Status(s): Completed

Reviews: This is one is another old one but it's a good simple, relaxing one with mostly action and some romance.

Flame of Recca

Author(s): ANZAI Nobuyuki

Status(s): Completed

Reviews: The title page looks awesome right? This is a romance/action with a very straightforward 'tournament' type of action. It is a very long manga and good