I’ll second the reccomendation of Death Note.
And there’s also Fruits Basket, and since I’m bad at summarizing things, wikipedia page here: http://en.wikipedia.org/wiki/Fruits_basket (anything past the story section has spoilers though) I don’t know whether you’ve seen the anime or not, but the manga goes far past where the anime left off, so it’s definately worth reading.
School Rumble, which starts off as a simple enough comedy set in a high school based around the love triangle of Harima (reformed delinquent) who likes Tenma (clueless average-looking girl) who likes Karasuma (sp?, wierd quiet guy) who likes curry.
There are wierd bits, like one girl can read the minds of boys who like her and Harima comes to understand animals, and Karasuma may or may not be an alien or a kappa.
The cast keeps expanding, which may cause difficulty in keeping track of some of the minor characters, but it’s a very funny series.
Also, the anime seems to have followed it EXACTLY (only read to volume 6 so far).
Evangelion. You’re wasting your time until you’ve read it, and if you already have, good job.
I’m actually staying away from that one for religious reasons, if you can believe it.
I can. That actually makes sense for you. 
Darker Than Black
I’m in the middle of the anime for this one. It’s supernatural mixed with conspiracy. When the Heaven’s Gate and Hell’s Gate appeared on Earth all the stars were blacked out and replaced with false stars. These stars are somehow tied to powers granted to certain humans. In exchange for the use of these powers they are compelled to ‘complete the contract’ after each use. Because of this they’re called Contractors. If they don’t complete the contract their free will is taken away from them and they become Dolls. Dolls are emotionless beings who can only do what they’re told.
Contractors become a valuable commodity for national defense and terrorists. The current story arc I’m in involves a shadowy organization who uses Contractors, Dolls and a human handler to search for something called a Star Fragment that’s being competed over with various governmet spy agencies and the Japanese Special Police Force dedicated to investigating Contractor related cases.
I didn’t realize there was a DtB manga.
If I didn’t like Excel Saga or Pani Poni Dash, I doubt I’ll like FLCL from what I’ve heard. The other one looks really depressing.
20th Century Boys for AN AMAZING PLOT and good artwork. Really, it’s a stunning read. Definitely check it out.
Its about this group of kids who used to play around and created this fictional story of how a bad guy will take over the world in the future. When these kids turned into adults, it turns out this story is coming true.
It goes back and forth between the past and the present, and its a really interesting story. Done by the same author of Monster, another manga I recommend. 20th Century Boys is much better though.
Oh! I had heard of 20th Century Boys, but did not know about its authorship. This bears a looking-into, now.
More recommendations:
If you liked FMA, you might want to try out the manga. The two diverge in hugely important ways. Parts of the manga you will have already seen in the anime, though.
Card Captor Sakura, by Clamp (the people behind X/1999). Ok, the art is over-effeminate, but the character is a little girl, so what of it? The main character is a Japanese schoolgirl, opens a book she finds in her archeologist father’s basement, releases a mass of elemental creatures who the book’s guardian (rule #2 broken - he’s small-animal mascot) informs her she’ll have to recaptue, OR ELSE. The OR ELSES in the sereies are always made out to be more dire than they are. The funny thing about this series is that it manages to be absolutely the most comfortable little story I’ve ever read. There’s none of the creepiness the internets has made it out to have, and unlike the animated version it follows a linear plot not restricted by a monster-of-the-week format. It’s understandable to pass it if the idea of the series makes you gag, but if you want some supernatural action, downright lovable (but in no way over the top or exaggerated) characters, and a bit of warmth in your heart., go for it. For the record, Clamp can’t draw adults without making them tall and angular, for some reason. Since this series focuses on smaller characters (whether children or creatures), though not exclusively, their style is much more pleasing to the eye.
It said it was serialized in Monthly Asuka on Wiki.
It’s morbid. Wouldn’t say it’s depressing.
Now you’ve got me wondering if I should read about the magical girl, ha. I’ve started reading Tsubasa Reservoir Chronicle (screw all that odd capitalization)
which uses a lot of the characters from other Clamp works in different dimensional settings, and I really enjoy it. The artwork doesn’t seem overly girly, but it’s well done, and the story has a lot of places it can go.
I’m trying FMA next since I love love love the anime franchise, but I’d like to read the light novels in addition to the manga. Are any of those out in English?
edit - I’m very sorry about not explicitly making recommendations. :\ The only manga I made a point of reading were Fruits Basket and Hellsing… what a combination, right? I really do like Tsubasa, though.
Somebody who likes Tsubasa I stopped watching Tsubasa after the 5th or 6th episode :[ My beef with it is that the characters talked like they were actually slightly mentally retarded in that they had to think about every sentence for about two seconds and then slowly enunciate out a reply (I also noticed this in CCS) and they seem to have no problems with setting up the plot for Pokemoning it up (Alright it’s TIME TO GO TO THE 59TH WORLD TO COLLECT THE 59TH FEATHER YEAHHHH!!!)
Why hasn’t Hellsing been posted yet?
Come on. Nazi vampires and werewolves.
Yeah, I’m not much of a goth person.
I tried MAR and was sorely disappointed. There was barely anything in the entire first book that actually caught my interest. I have Death Note on reserve at the library and, well, we’ll see. 
Hellsing isn’t about goth. It’s about a guy in a red hat shooting shit with a big gun. It’s seriously fantastic, with some of the greatest characters ever. Alucard is way overpowered, but eh.
“Nazi vampires and werewolves” don’t really sound like something I’d appreciate.
Your loss.