666 Satan
Aflame Inferno
Agharta
Aiki
Air Gear (HIGHLY RECOMMENDED)
Akumetsu (HIGHLY RECOMMENDED)
Amatsuki
Bamboo Blade
Beelzebub (pure crack)
Berserk
BioMega
Black Cat
BLAME! (a MUST read)
Chrome Shelled Regios
Claymore
Chocolate Cosmos (recommended)
Deadman Wonderland
Digimortal
Dragonaut - Resonance
Eden no Ori
Endless Eden
Fairy Tail
Flunk, Punk Rumble
Full Metal Panic
Ga-Rei
Gintama
Gyakusou Shoujo (highly recommended)
High School of the Dead (highly recommended)
Himiko-Den (highly recommended)
HOTEL (A MANDATORY READ)
I Love High School (highly recommended)
Id
Iketeru Police
Jack Frost
Junk - Record of the Last Hero
Kami to Sengoku Seitokai
Koi Kara Hajimaru
Lion Maru G
Macross Frontier
Maken-Ki
Manyuu-Hikenchou
Minami-ke (A MUST READ)
Mx0
[Naked Star | Sapphire Star | West_Side_Street] (highly recommended) [THIS IS HENTAI] - by Oh Great! however.
Nemureru Hoshi
Net Sphere Engineer
NOiSE
Psycho Busters (highly recommended)
Psyren
Raiders
Rappi Rangai
Rave Master
Reideen
Rosario Vampire
Samurai Deeper Kyo (highly recommended)
School Days
School Rumble
Sekirei (OPPAI!!!!!!!!!!!!!!!!)
Shina Dark
Shinobi Life (recommended)
Silvery Crow (recommended)
Sket Dance (highly recommended)
Star Ocean
Sunabozu
Superior (HIGHLY RECOMMENDED)
Suzuka
Suzumiya_Haruhi_no_Yuutsu
Princess Lucia (recommended)
Tende Freeze (if you liked Aiki, you'll like this one)
Tengen Toppa Gurren Lagann (epic)
Tenjou Tenge (HIGHLY RECOMMENDED)
Threads of Time (highly recommended)
Tiny Boobs Giant Tits History (hentai, recommended)
To Love-Ru (oppai and ass)
Tokage (recommended)
Tsubasa Reservoir Chronicle (awesome at first, gets convoluted later. Need to have read Card Captor Sakura and SEVERAL other major CLAMP stories including xxxHOLiC first in order to understand this series. Recommended)
Ublet Blatt (recommended)
Umi no Misaki (recommended)
Unbalance x Unbalance (recommended)
Veritas (HIGHLY RECOMMENDED)
Wolf and Spice (recommended)
Worst (HIGHLY RECOMMENDED)
xxxHOLiC (A MUST READ)
Yuutai Nova
Yureka (recommended)
Zero
Go read these.