On my Dell S2309W (but not my Dell 2009W), the Arqade Meta background flickers. If I zoom in to 150% or more (I'm guessing that turns the 1-pixel rows into 2-pixel rows), the flicker is eliminated.
I don't know much about LCDs, I've heard about "pixel walk" but I don't know if this is that, but tweaking the non-black pixel (45, 45, 45) to something with a hint of color (50, 50, 45) seems to abolish it. A slightly different grey (50, 50, 50) still gives me flicker.
Example (run in JS console F12...):
document.body.style.background="transparent url(http://i.imgur.com/n0wE8VJ.png) top center";
document.body.style.background="transparent url(http://cdn.sstatic.net/gamingmeta/img/bg-body.png?v=42) top center";
Slightly related, probably because of my monitor freaking out about 1 px grey/black patterns, I'm also able to easily see the difference between "bg-header.png" and "bg-body.png". The "header" background grey (used in the footer) is 1-bit brighter: (46, 46, 46).