O&M, of course, is at best only adequate as a moneymaker. And someone else pointed out that the "Schlock Mercenary" guy has made noises about getting another job again. (I wonder if his huge salary allowed him to save up enough not to worry about making ends meet for a while.)Schlock Mercenary: Read the "About the author" section, where it describes how Howard quit his (allegedly six-figure income) job at Novell, in order to do the strip full time. Goats by Jon Rosenberg; Again, check the "about" page, where he says he lives in New York City and makes his living doing the comic strip.
There's no similar page for Penny Arcade, but they employ as many as five people, collected something like half a million bucks in Child's Play donations last holiday season, and now have their own Expo (PAX, the Penny Arcade Expo) coming into it's third or fourth year, which had something like 100,000 atendees last year. The rumor going around is that the two of them earn something like $2 million a year.
Scott Kurtz has been living off PvPOnline for four or five years now, including now writing for Image comics, Pete Abrams of Sluggy Freelance has been rumored to be making over $100K a year off his strip (as does Goats, supposedly) and Rich Burlew of Order of the Stick is rumored to have sold over $80,000 in books in the last two years.
Moving down the ladder into more hearsay material, supposedly Jay Naylor makes his living with his two comics (Better Days and New Worlds, although those are just draws for his for-pay furry porn works) Michael Poe of Errant Story makes his living off the strip and related artwork, as does Al from Poisoned Minds.
Two years ago, Randy from Something Positive challenged readers who were, at the time, complaining of late updates, to donate to him a years' salary, after which he'd start doing the comic full time. In two weeks he'd amassed over $18,000, and within a month had his goal of $22.5K. He's been doing the strip as a day job, and making more at it, ever since.
Kris Straub started out with Checkerboard Nightmare and now does Starslip Crisis as a day job. In fact, almost all the Blank Label comics are the authors' "day jobs", with the exception of Greg Dean, who is in school to become a chef (but the strip still helps make ends meet.) Dave Kellet just pulled Sheldon OFF a newspaper syndicate (!) so that he could make more money self-publishing.
The list goes on. Ozy & Millie, Dominic Deegan, Questionable Content, Ctrl+Alt+Del, Sinfest, Sam & Fuzzy, MegaTokyo, Girl Genius, (although that one started out a print graphic novel first,) Least I Could Do, the author of Filthy Lies is actively trying to gain readers so he can make it his day job...
Could the rest of the information be accurate? Is there hope for those who want to make a decent career out of web cartooning? (Those who treat it like a hobby surely will not have such economic success.)