
You're free to ink whatever permanent monstrosity you want on your body, but when it comes to technology tattoos, be careful! Some tech tats have expiration dates. All technologies will eventually be replaced, but some will be remembered more fondly than others—and some won't be remembered at all.
Here are a few unfortunately souls who fell victim to having obsolete—or otherwise terrible—tech totems tattooed all over their bodies:

QR Codes
The neat thing is if you hold your phone up to this and scan it you're sent to a website that just says "I AM A MASSIVE TOOL" in giant blinkytext. I assume.

Zune
At least now that Zune is pretty much officially dead you can pass this off as ironic? [ClicZune]

Geek Squad
In fairness, it's entirely possible this person was just branded after falling behind on Best Buy interest payments. [Geeky Tattoos]

Gateway Computers
Even if—even if—Gateway used to be a decent enough PC brand to sear onto your flesh, there's no way the cow logo is worth it. [Orange County Register]

The Blackberry Storm
At least it's not a PlayBook, I guess? [Crackberry]

Xanga
I just wish we could read the emo Xanga entry that was written in the immediate aftermath of this. [Biz Stone]

MySpace
In fairness, back in 2005 even Rupert Murdoch thought MySpace was a great idea. [Complex]

Adobe Air
The most forgettable of all Adobe products, celebrated in the least forgettable fashion. [ReadWriteWeb]

Sidekick
Actually, you know what? Screw it. I'd get this tomorrow [Geeky Tattoos]
DISCUSSION
Not so much tech, but if I were to get a tattoo, it would be some variation on the Pioneer Plaque. Maybe just the Hyperfine transition of neutral hydrogen.
[en.wikipedia.org]