I hope one of the Free Comic Book Day books you picked up was IDW's 'Judge Dredd Classics'.
This book takes some of the best and most love Judge Dredd stories, gives them to you for free and hopefully this will hook you into getting some of the books and collections that IDW has to offer.
Judge Dredd - The monthly series by Dwane Swierczynsji and Nelson Daniel has the look and feel of the old school '2000 A.D.' stories; short, to the point and full of explosions.
Judge Dredd Year One - A look at the rookie year of Dredd by Matt Smith and Simon Coleby.
Coming in July is 'Judge Dredd Classics'. The original stuff but re-colored! This is a must have.
The fall of 2013 brings us 'Judge Dredd Mega City 2' by Douglas Wolk and Ulises Farinas! I don't know anything about this book but it looks awesome!
And for those who have to have it all in one book, look for 'Judge Dredd Complete'! These hardcover themed collections The two volumes available now feature the art of the Dredd masters; co creator Carlos Ezquerra and the master himself, Brian Bolland!
See why I rank Judge Dredd one of the greatest comic book characters of all time. And thanks to IDW you can see a whole lot of it!