Archie’s still going strong.
DC’s Plastic Man is pretty good (but selling badly, and due to be canceled, soon).
Marvel’s put out a couple one shots that were quite funny recently - Marvel Monsters (Devil Dinosaur, Where Monsters Dwell, Fin Fang Four, and at least one more I’m blanking on the title) Wha…? Huh? and GLXmas. (Marvel Zombies is also good for a laugh, but was primarily a zombie book that had humour, rather than a humour book.)
Second and third tier companies are usually good for humour books, too, although I’m blanking on any ongoing, current titles (rather than ended series or one-shots).
Books that are humourous, but aren’t primarily about humour, are also not too hard to find: Ted Naifeh’s books are not humour books, but they’re quite funny (Polly and the Pirates#2 had me giggling the whole way through.). Hack/Slash is mostly a slasher/action book, but the dialogue is usually funny, and the situations are often funny (in the sick way slasher flicks often are), and laden with in-jokes. The convention scene in Comic Book Mayhem and the ‘searching the hotel rooms’ bit in Girls Gone Dead are good examples of this.
Then there’s the books that are harder to classify in this way, such as the new Army of Darkness vs Re-Animator book. Not quite as goofball as AoD (the movie…I haven’t read the older comics), but far from serious. And Lobo still turns up from time to time (most recently in Authority/Lobo Spring Break Massacre) for ultraviolent giggles (seriously…insanely violent, and thus insanely funny (if you’re into that kind of humour)).
Check out CABLE & DEADPOOL if you like humor, or pick up the DEADPOOL trades. Hilarious stuff, it helps if you’re a bit familiar with superheroes and such because Deadpool does a lot of riffing on folks like Spider-man and the X-Men.
For an idea of what it’s like, here are some scans. Deadpool gains the power of THOR! “By Oprah’s chins! Mine hammer doth return to me as though twas a Blockbuster rental!”
Gerome, if someone said to me that Judd Winnick’s Barry Ween series were the funniest thing ever put to paper, I might argue, but not very hard. Winnick’s currently toiling for the tall dollar at DC, but there are four Barry Ween TPB’s available at your local comics store. Unless the store totally sucks, which it probably does, but you can tell him to order them for you – Oni Press is the publisher.
I think the OP was asking for comic books, not comic strips. As far as comic strips go, Pearls Before Swine is pretty funny. As for books, don’t know- don’t read 'em.
True, I’m already well served for webcomics and strips and whatnot. I was after more your monthly publication, because I get kind of sick of this ‘gritty realism’ in comics every now and then and actually want to, you know, laugh occasionally.
Anything by Dan Slott is funny: She-Hulk, Great Lakes Avengers, and Spider-Man/Human Torch: I’m With Stupid. The majority of these are in trade paperback form. He has a new Thing miniseries out, which I have to assume is also comedic in tone.
Usually anything by Keith Giffen and J.M. DeMatteis is funny: Formerly Known As the Justice League, I Can’t Believe It’s Not the Justice League, Defenders, and Hero Squared. Of course, they started working together on one of the great comics of the '80s: Justice League International, a very sitcom/reality show-esque take on superhero interrelationships, which was very much ahead of its time.
Kyle Baker has some hilarious original graphic novels: Why I Hate Saturn, The Cowboy Wally Show, You Are Here, and I Die At Midnight. I tried his Plastic Man series, but even though it’s a “humor comic,” I didn’t find it terribly funny.
The original twelve issues of The Tick, back when Ben Edlund* was writing AND drawing it, were also wonderfully funny. Like most of the above, they are collected in trade paperbacks.
*Whedonites, listen up! Ben Edlund, creator of The Tick, was a writer and producer on Joss Whedon’s Angel and Firefly TV series!
Brian Michael Bendis’ Fortune and Glory graphic novel, about his experiences in Hollywood, is also drop-dead funny.
Finally, Gail Simone also has a real handle on humor writing, from her too-short run on Marvel’s Deadpool (#65-69) and Agent X (#1-7 and #13-15). She injected plenty of humor into the recent Villains United miniseries (which isn’t a comedy, just so you know), and her Birds of Prey run is supposed to be sublime.