Mods Minecraft has taken from

Next time someone says Mojang doesn't need modders, show them this!

NOTE: We're not implying that Mojang has taken ideas from all of them. All we know is that those things were in mods a long time before they got added by Mojang.

• Pistons

• Superflat biomes (a lot of Bukkit plugins)

• Redstone Lamp

• New commands (Bukkit plugins like Essentials)
• Written books (Can't recall name; also, bukkit plugins)
• Emeralds (arguable - emeralds in Minecraft are very different in usage than RP2's old Emeralds)
• Ender Chests (EnderStorage)

• Quartz blocks (reminiscent of RP2 Marble)
• Hopper (BuildCraft Chute, Better than Wolves Hopper)
• Proper snow heights (Better Snow)

• Coal Block
• Horses (Mo' Creatures/Simply Horses) (“Creation assisted & inspired by DrZhark of Mo' Creatures”)

• Actual graphics configuration options (OptiFine)
• AMPLIFIED (many custom biome generators)
• Extra fish (Aquaculture)
• Extra trees, new biomes, flowers (ExtraBiomesXL, Biomes O' Plenty)
• Shaders
• Stained Glass (too many to list; for example, TCon and Metallurgy)

• Different wood types for doors, fences, etc. (a few mods did that already)
• Armor Stand (BiblioCraft, some customization stuff from Statues)
• Customize World Settings (BWG4, ATG)
• Fancy doors (Carpenter's Blocks)
• Improved fences (Fancy Fences)
• Banners (CraftHeraldry)
• Iron Trapdoors (I saw a mod like that in 1.6.4, I promise)
• Slime Block (a combination of frames and Bounce Pads from TCon)
• Underground stone types (RP2, Artifice, Geostrata, Underground Biomes)
• “Grass blocks, dirt, sand, red sand, stone, Netherrack, bedrock, and TNT all have their top texture randomly rotated” (OptiFine)
• “Threaded chunk rendering” (OptiFine)
• Various new command line commands (Bukkit plugins like Essentials)