Since all the obvious have already been listed I'll just had "Seven Miles A Second" by David Wojnarowicz. If you ever come by it, please give it a honest try.

My faves:

When I need to laugh -
Barry Ween
Why I hate Saturn
Anything by Phil Foglio (especially Myth Adventures and Buck Godot)
The Trouble with Girls

When I want some Superheroey goodness -
Camelot 3000
Crisis on Infinite Earths
The New Teen Titans - The Janus Contract
Iron Man - The Armor Wars
X-Men - the Dark Phoenix Saga
Nick Fury vs. S.H.E.I.L.D.

When I want something Science-fictiony -
Ghost in the Shell
Outlanders
Appleseed
Grendel - War Child

When I want something deep -
Watchmen
Sandman
Give Me Liberty
Alan Moore's Swamp Thing
Sin City

When I want something romantic -
Video Girl Ai
Omaha the Cat Dancer

When I want to cry (literally) -
9-11, vol. 1 &2

Besides Watchmen and The Dark Knight Returns...

From Hell and Lone Wolf and Cub.

Batman : Sword of Azrael
Batman : Knightfall Vol.1 and 2
Batman : Knightsend
Batman : Venom

Christin/Bilal: The Hunting Party.
A great graphic novel that tells the tale of leading party cadres from the communist parties of the eastern bloc, coming together for a hunting party. A fantastic allegory of the soviet political system.

Other than the afore mentioned Watchmen and Dark Knight Returns, I have to go with Hellboy: Wake The Devil by Mike Mignola.

You said it. With a bit of exagaration: it's one of the best GNs of the last century.

- nenad

Thanks, Nick1228
Save some room on your list for TRENCHES. This one's a doozy, and I'm really proud of it!
Now I'm working on a 300-page monster called THE MASTERPLAN. It's sci-fi ala Arthur C Clarke and Stephen Baxter.

My favorites are WATCHMEN, DK, JLA: HEAVEN'S LADDER, 2001 NIGHTS (awesome sci-fi manga) JIMMY CORRIGAN, GHOST WORLD and SKIBBER BEE BYE.

Still my favorite: one of the first modern American GN's- Sabre by Moench and Gulacy.

Close runner up: Sam Glanzman's first Sailor's Story. I consider this one of the truly important works in American comics-- Sam's reflections on his true-life experiences aboard the U.S.S. Stevens during WW2. Too few have read it. That's their loss.

Favorite European graphic novels: Hermann's Jeremiah GN series-- all of them (looks like the showtime series is really going to turn the whole concept into a slab of butchered hog meat); A bunch by Alphonso Font (my favorite Euro arteest); the Siberians by Hugo Pratt; the Ethiopians by Hugo Pratt.

And a whole bunch more.

bone vol#1 i love this book