Canon dump!
As a handy reference for me, here are the links to the strips in which Liet appears. Translation credit goes to the folks who posted them, of course.
Main Storyline:
Chapter 4.
Chapter 5.
Extra Stories:
Bloody Sunday 1905.
Lithuania's Outsourcing, part 1.
Lithuania's Outsourcing, part 2.
Lithuania's Outsourcing, part 3.1.
Lithuania's Outsourcing, part 3.2.
Lithuania's Outsourcing, epilogue.
Halloween comics.
Polish-Swedish Wars.
After Tannenburg.
Checkmating Poland.
While You Were Gone.
It's Sealand-kun!.
Bakki Baki. Also known as "that strip that's named for the sound made by Liet's fingers breaking." No, really.
Making British Food. Also, Youth and Old Man.
The World Conference.
Redrawn in Color.
Cleaning Out the Storage.
The Extra Christmas Strips. You must be logged into hetalia to view these.
Drama CD:
Downloads and track listings.
G5 Task Force translation.
Main Storyline:
Chapter 4.
Chapter 5.
Extra Stories:
Bloody Sunday 1905.
Lithuania's Outsourcing, part 1.
Lithuania's Outsourcing, part 2.
Lithuania's Outsourcing, part 3.1.
Lithuania's Outsourcing, part 3.2.
Lithuania's Outsourcing, epilogue.
Halloween comics.
Polish-Swedish Wars.
After Tannenburg.
Checkmating Poland.
While You Were Gone.
It's Sealand-kun!.
Bakki Baki. Also known as "that strip that's named for the sound made by Liet's fingers breaking." No, really.
Making British Food. Also, Youth and Old Man.
The World Conference.
Redrawn in Color.
Cleaning Out the Storage.
The Extra Christmas Strips. You must be logged into hetalia to view these.
Drama CD:
Downloads and track listings.
G5 Task Force translation.