Here's some quick manga recommendations from what I can currently remember:
Until Death do us Part - Badass Blind Swordsman protects a girl that can foresee the future. Better than it sounds, Currently Ongoing.
School Rumble - Funny and quirky characters. Finished but you'll need School Rumble Z for more..."Closure"(?)
GTO - Ex-gang member turned teacher teaches kids to enjoy life through his unique hotblooded and will-usually-make-you-end-up-in-jail ways. Finished.
Vinland Saga - Vikings doing what they do best. Said to make you grow chest hair as you read. Ongoing as well.
Ubel Blatt - a swordsman's quest for vengeance against those who betrayed and killed him and now call themselves the seven heroes of the land. Not for kids, Currently on Hiatus.
SHINA DARK - The demon lord awakens and countries the world over send over a thousand sacrificial maidens to the island in an attempt to satisfy his "legendary lust" and protect their lands from his fury. But the series is actually a comedy so he's more interested in naps and fishing than world domination. Finished(?) with 4 volumes.
Sankarea - ecchi horror manga about a zombie-obsessed boy who discovers how to resurrect the dead and as a result acquires a zombie girlfriend. Seriously. Really.
Lying Mii-kun and Broken Maa-chan - short read but interesting. Finished.
Brain's glitchin'...gotta' do it quick. Letsee'...some more finished manga's that might pick your interest are: Arcana, GA-REI, Tsukihime, LOCK-ON!, Black Lagoon, Gunslinger Girl, Blood Alone, Yotsubato! and *GLITCH* Memory Error
Bleh...Hmm, 4-koma manga's don't interest you huh?