Resources and Generators: Asmor’s Generators, Book of NPCs (v2), Chatty’s Tool Roundup, Kiznit’s Combat Crib Sheet
Character sheets and cards: iplay4e, Javascript character generator, Simple play sheet(pdf), and Dragon Avenue’s collection
WotC Site: 4e Errata, Compendium, and character builder.
Fan made: Greywulf’s Character of the Day, Catfolk and Ninja, Stored Rituals
Adventures and Other Resources: P3’s Campaign Starters, Forgotten realms wiki
Five Blades of Bahamut (a great custom setting by Chris Chinn) Setting Overview, Cults of Bahamut, Cults of Tiamat, Quest Seeds, Airships, Deities, Creation Myth, and Monsters