Superflat Preset Generator: http://www.minecraft101.net/superflat/

Commands Include: Tellraw / Execute / Titles / Custom Signs / Custom Books

Tools include: Firework Crafting / Flatworld Generator / Mob Generator / Enchant Calculator / Banner Crafting & More!

Other Summon Command Generators:
http://www.summon-helper.net/

http://www.minecraftupdates.com/summon-command

Xisuma's Custom Banners: https://xisumavoid.com/banners/

http://www.minecraftcrafting.info/

Don't know how to craft something? Simply visit this site!

Mobs & Entities / Potion IDs: http://minecraft-ids.grahamedgecombe.com/entities

Info on all versions of Minecraft
Includes: Recipes, Tutorials, Redstone Circuits and more!

Download Skins:

http://www.minecraftskins.net/
http://www.minecraftskins.com/
http://mcskinsearch.com/browse

Skin Editor:

http://www.silvergames.com/minecraft-skin-editor
http://www.minecraftskins.net/skineditor
http://www.minecraftskins.com/skin-editor/

Resource Packs & More Skins:

http://novaskin.me/
http://www.worldofminecraft.com/Downloads
http://www.minecraftdl.com/
http://www.minecrafttexturepacks.com/
http://www.curse.com/texture-packs/minecraft/downloads