This thread's to keep track of cool commons I find for Pauper EDH.
Feel free to post thoughts / suggestions. I'll try to keep the main posts free for reference.

[u]Fatties[/u]

Colourless
Ulamog's Crusher
Hand of Emrakul

[u]Non-basic Lands[/u]

There are a decent selection of non-basic lands at common ...
Colourless / All Colours
Command Tower
Darksteel Citadel
Evolving Wilds
Opal Palace
Rupture Spire
Shimmering Grotto
Terramorphic Expanse
Transguild Promenade
Unknown Shores
Urza's Mine
Urza's Power Plant
Urza's Tower

Single Colour
All the coloured Cycling lands
All the artifact lands

Dual Colour
All the Guild Gates
All the Ravnica Bound Lands

Triple Colour
All the Panoramas

[u]Commander Protection[/u]

At common, it seems much easier to give your command shroud than hexproof or indestructible ...
Colourless
Whispersilk Cloak

White
Inviolability

Blue
Alexi's Cloak
Anti-Magic Aura
Diplomatic Immunity
Neurok Stealthsuit
Robe of Mirrors

[u]Mana Sources[/u]

This is not a format which is short on mana ramp ...
Colourless
Darksteel Ingot Common in Darksteel set
Fellwar Stone
Fractured Powerstone
Mind Stone
Manakin
Opaline Unicorn
Prismatic Lens
Pristine Talisman
Manalith
Scuttlemutt
Sisay's Ring
Sol Grail
Springleaf Drum
Blue
Apprentice Wizard
Dreamscape Artist
Silver Myr
Azorius
Azorius Cluestone
Azorius Signet
Boros
Boros Cluestone
Boros Signete
Dimir
Dimir Cluestone
Dimir Signet
Mistvein Borderpost
Golgari
Golgari Cluestone
Golgari Signet
Gruul
Gruul Cluestone
Gruul Signet
Izzet
Izzet Cluestone
Izzet Signet
Rakdos
Rakdos Cluestone
Rakdos Signet
Selesnya
Selesnya Cluestone
Selesnya Signet
Simic
Simic Cluestone
Simic Signet

[u]Card Sources[/u]

I'm only listing repeatable effects here, not "ETB->Draw a card" style cards
Blue
Curiosity
Ninja of the Deep Hours
Ophidian Eye
Rhystic Study

Green
Snake Umbra

Dimir
Helm of the Ghastlord

Izzet
Quicksilver Dagger

[u]Combo Pieces[/u]

Mana
Gilder Bairn
Pentad Prism

[u]Tutors[/u]

Can't find may of these ...
Colourless
Expedition Map

[u]Reanimation[/u]

Black
Death Denied
Disturbed Burial
Grim Harvest
Shattered Crypt

Green
Repopulate kinda

[u]Board Wipes[/u]

Can't find may of these ...
Red
Fireball

Wat.

Ullamog's Crusher is common?!

*whistles innocently and doesn't make any changes to his deck*

Finding it quite tricky to get decent card draw outside blue, anybody seen anything?

Fireball sort of a board wipe...

Got to love this card :)

coiling oracle

Most expensive common I've bought :P

Good card, but I wasn't planning to list all the draw-a-card cards, too many to speak of!

Well, it's not just draw a card. It's an Explore as well.

Added a metric fuck ton of mana ramp cards, some commander protections and a spattering of other stuff.
Blue is certainly winning the "largest number of repeatable effects" contest at the moment, but that's probably some selection bias as I've been looking at that colour more than the others thus far.

Added a selection of non-basic lands.

Command Tower most amazing common land EVER. :lol:

Not sure exactly how to categorize her, but Ivy Lane Denizen seems like an allstar card if you're playing green.