This is really outdated, some of the heads have changed and I'm not updating it anymore. If you're looking for an updated list, I recommend this one.

I found out a way in wich you can make it look like you are using microblocks while you actually aren't.
If you saw the picture above you might have already guessed how I did it, if not let me explain it to you.
since 1.4 or something you are able to have the heads of players and some mobs, if you make someone's head you mostly use it for a head trophy or something, but if you make the head of a player with a block as his/her head then it looks like a microblock.
I found this while messing with playerheads I was spawning hads of names that I thought existed and I came across a person named stone who had a log haed head so I thought it was kinda cool and I started searching for more.
I went to [url/]mcskinsearch.com/[url] there you can find skins that are actually being worn by someone, and I just went through the first 245 pages and I found27 different poeple with different blocks as thar heads.
So here's the list of names and blocks (case sensitive)

Block Name
Cobblestone jackmyrod
Grass joppari
Dirt boker1
Diamond ore acissejxd
Wooden log MHF_OakLog
Stone Robbydeezle
Jukebox C418
Sand Praxis8
Obsidian loiwiol
Cactus MHF_Cactus
Redstone ore annayirb
Stone Brick Cakers
Lava XX_JaKoB_XX
Chest MHF_Chest
Jack o lantern Loon375
Tnt MHF_TNT
Gold block teachdaire
Redstone block Faceman2301
Orange wool titou36
Sponge pomi44
Bedrock dylansams
Netherrack Numba_one_Stunna
Snowy grass block Creeper999
Piston JL2579
Sticky piston Panda4994
Mossy cobblestone agiantstick
Melon MHF_Melon
Pumpkin MHF_Pumpkin
Cake MHF_Cake
Wooden planks MattAttackAlpha
Wooden planks? MHF_Question
Wooden planks! MHF_Exclamation
Wooden planks^ MHF_ArrowUp
Wooden planks> MHF_ArrowRight
Wooden planks< MHF_ArrowLeft
Wooden planksv MHF_ArrowDown
Bookshelf BowAimbot
Redstone Lamp (on) AutoSoup

the ones below aren't really blocks in minecraft but they do look cool
Computer Monitor CoderPuppy



if you happen to find any please leave a comment and I'll update it.
if you are someone who is willing to have a block as your head for the rest of your lifetime and you need a skin for that, just mail me ([url=mailto:rcxcrafter@gmail.com]rcxcrafter@gmail.com[/url]) I'll make it for you. I really hope you liked this.
-RCX