Game Web Sites and Officials Blogs:
Dungeons and Dragons Home Page
D&D 5th Edition Unearthed Arcana
Game SRD’s:
Dungeons and Dragons 5th Edition SRD (there are others you can google, too)
Game Running Resources:
Roll20 (Don’t run an online campaign without it!)
Kobold Fight Club Encounter Builder
Hero Labs tools for character and state tracking
Homebrew Sites and Inspiration:
Homebrewery for beautifully formatted Dungeons and Dragons 5th edition homebrew material