Because it appears to be customary:
A link wherewith you can give me street team points. Even though I probably don't know you, I assure you I deserve it. Thanks. (The links below have my referral on them too, just so you know.)

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In chrono-prefero-noparticulo order

Shirts I want:
Moby Was A Consumer
Oh My Virgin Eye
Captain Awesome
Legendary Design Failure
Fish Tank


Shirts I want (but can't have because they haven't been printed yet*):
F.A.B. Mr President
More coming...


Shirts I like, but probably won't buy:
Deerie
Afternoon Delight
The War Against Work

Shirts I own:
Follow It
You Sank My Battleship
Angels and Demons
Pessimistic or Optimistic? (Thanks to ir0cko!)
Dark Side of the Garden
This is not a Pipe
Lost A Wheel
Satan's Little Helper
The Madness of Mission 6
Fantastic Typewriter
Steak and Eggs
The Average Bear

* Alright, I'm willing to be realistic on this one; there's a good chance these won't ever get printed. Still, a guy can dream.