The best bet for "Free Comics Day" appears to Fantagraphics' "Unseen Peanuts" comic.
http://www.fantagraphics.com/blog/uploaded_images/UnseenPeanutsCov-789839.jpg
Links
Cartoonists
Sergio Aargones
David B
Peter Bagge
Carl Barks
Lynda Barry
Vaughn Bode
Brian Bolland
Chester Brown
Ed Brubaker
Eddie Campbell
Del Close
Daniel Clowes
Jack Cole
Johnny Craig
Robert Crumb
Jack Davis
Jennifer Daydreamer
Dan Decarlo
Kim Deitch
Evan Dorkin
Julie Doucet
Dennis Eichhorn
Will Eisner
Bill Elder
Bud Fisher
Renee French
Neil Gaiman
Bill Griffith
Milt Gross
Tom Hart
George Herriman
Ben Katchor
Walt Kelly
Jack Kirby
Bernie Krigstein
Harvey Kurtman
Jon Lewis
Jay Lynch
Larry Marder
Sheldon Mayer
Max
David Mazzuchelli
Winsor McCay
Mike Mignolia
Alan Moore
Josh Nuefeld
Harvey Pekar
John Porcellino
Spain Rodriguez
Scott Saavedra
Joe Sacco
EC Segar
Seth
John Severin
Samm Schwartz
John Stanley
Carol Swain
Cliff Sterrett
Jacques Tardi
Ty Templeton
Bill Watterson
Shannon Wheeler
Basil Wolverton
Wally Wood
Jim Woodring
Aleksandar Zograf