ESC/POS Simple Converter Extension - Daniel K.
Experiences with the Jimdo.com ESC/POS Converter - @Bob_Holden
[PAID] Thermal Printing extension (Bluetooth/Network) - mmnettime
Printing in ZPL from text blocks - David_S, Juan_Antonio, Peter, ChrisWard
Reference Material
Epson ESC/POS(R) Reference Manual