Games Workshop offers an “essential” edition of its Warhammer 40K rules free for the downloading.
Ironhands has a tutorial on building a Games Workshop type Thunderhawk gunship from styrene and bits of toys. It’s a nice and imaginative scratchbuilding project.
I’ve been painting Blackstone Fortress figures lately, and have found the Midwinter Miniatures videos on YouTube helpful.
Chain of Command: The Horus Heresy is a modification of Two Fat Lardies’ Chain of Command Rules for the Warhammer 40K Universe.
What A Tanker 40K is a modification of Two Fat Lardies’ What A Tanker Game for the Warhammer 40K Universe