I can throw out a few additions and updates. In particular, the list I originally posted had some rather terse descriptions that could use a bit of updating. Here are some expanded blurbs:
The Dark Knight Returns - Frank Miller's satire inspired an entire industry towards grim and gritty, proving that they didn't get the joke. Which is a pity, as TDKR is one helluva adventure, mixing grim futurism with the perfect expression of Bruce Wayne as an old, tough as nails bastard who refuses to quit. The one Batman trade everyone should read.
Batman: Year One - Showing that Miller can write Batman as something other than vicious satire, this is a perfect example of how to take a classic origin story and expand it for a modern audience. Miller takes us from the tragic death of Bruce Wayne's parents to the finished incarnation of his crime fighting persona.
DC Universe - A collection of miscellaneous stories Moore did for DC, all of which are gems. Here's the rest of your essential Superman reading (including Moore's love letter to pre-Crisis Superman, "Whatever Happened to the Man of Tomorrow?"), as well as the acclaimed Batman story The Killing Joke.
(You may want to add a note at the end of the separate "Whatever Happened to the Man of Tomorrow?" description explaining that it's available as a stand alone or as part of DC Universe.)
Watchmen - Alan Moore's definitive deconstruction of the superhero comic. Dense, literate, powerful, this is the graphic novel that launched dozens of graduate theses and is cited, rightly, as a shining example of the idea that comics aren't just for kids. An excellent starting point for the new comics reader looking for something a bit more challenging.
Sandman - Neil Gaiman's acclaimed crossover modern fantasy about Morpheus, the lord of dreams, is filled with mythology, wonder, wit, and pathos. Reading this at the local coffeehouse will help you pick up hot hipsters. No, seriously.
V for Vendetta - A dystopian SF broadside against the horrors of Thatcherism, whose protagonist dons a Guy Fawkes mask and wages a campaign of terror against near-future totalitarian Britain. As good as the movie was, the comic is much better.
Y: The Last Man - Current critical and mainstream darling Brian K. Vaughn's thorough exploration of a single concept: What if there was a single male mammal left alive? Well, two mammals, namely a boy and his monkey questing through a post-apocalyptic, all-female society. A recent classic and very highly recommended.
Grant Morrison's X-Men - A recent take on old favorites, running wild with ideas and shifting away from the established soap opera formula. Our merry mutants, now a significant portion of the global population, begin to band together as an established minority, with Morrison looking at the impact this has on society and how the X-Men adapt to their new role. Don't worry, super-powered bad guys still get beat up. Inconsistent art, yet consistently awesome.
Joss Whedon's Astonishing X-Men - On the other hand, here you have the soap opera formula perfected, showing the X-Men fighting foes and interacting amongst themselves according to the classic format, but told with modern flair and plenty of wit by Whedon, with gorgeous art by John Cassaday. Between this and the Morrison run, you've got most of your X-Men needs covered.
Bone - Delightful all-ages adventure about a trio of odd creatures and their quest through a fantasy world, full of terrific characters, humor, and vast crossover audience potential. Self contained in one big honkin' volume, this is both the perfect gift for any younger family member you want to introduce to comics and a story you'll want to have on your own bookshelf.
Cerebus - Dave Sim's lifework started out as a Conan parody about a barbarian aardvark, became a epic, brilliant satire on politics, religion, and more, and then broke down completely around the same time Sim himself did. The second half of Cerebus is a very mixed bag, but that first half is some kind of brilliant and one of the finest examples of self-publishing in comics. The first volume shows the promise of the series to come, but is still rather rough around the edges; start with High Society and, when you're hooked, go back to the first volume.
Love and Rockets - Representative of indie comics at their finest, this collaboration by Los Bros Hernandez started in the early 80s as a series of off-beat stories with each brother going in a different direction. Jaime provided fantastic adventures about fringe LA punk culture as seen through the filter of pulp SF, with loveable
locas working as mechanics in odd settings and taking inspiration from female wrestlers, with the occasional monster rampage thrown in. Meanwhile, Gilbert's storyline about the daily lives of the inhabitants of
Palomar, a small Central American town, told warm, humanistic stories with a touch of magical realism thrown in. From this starting point, Love and Rockets evolved throughout the 80s into a masterful anthology series.
Maus - Art Spiegelman's Pulitzer winning biographical account of his father's survival of the holocaust (famous for it's depiction of Jews as mice and the Nazis as cats) and his autobiographical depiction of the effect learning his family history had on Spiegelman.
There, hopefully that'll help polish recommendations for some of the best comics on the list. I'll be back later with more descriptions and new recommendations.
Also, the list is a good resource, but it may be a bit difficult for a new reader to know where to start. Can we generally agree on a few core titles that should be recommended? Say a dozen at most, with bjork making the final call as to what should or shouldn't be included. I'm talking titles like:
Watchmen
The Dark Knight Returns
Maus
Sandman
Cerebus
Akira
Nausicaa
Monster
V for Vendetta
Y the Last Man
Astonishing X-Men
All Star Superman
Basically, a short list in the first post that says, "Hi, if you're completely new to comics and don't know where to start, here are titles that are consistently recommended and are considered classics. Read the descriptions, see what interests you, head down to the bookstore or library, and jump in!" The rest of the recommendations work well for folks who are already somewhat familiar with comics, but I think we need a starting point.
FnordChan