My Tugboat columns
The NTG styles (with Johannes Braams and Nico Poppelier)
The bag of tricks: about category codes, (see also), box manipulation, hyphenation, output routines, printing labels, letter spacing, about the loop macro, macros with optional arguments.
Technical stuff: An indentation scheme, Oral *cough* TeX, a parskip scheme, paragraph shapes, the TeX processors,
Tutorials: control sequences,
Other: About Lollipop TeX, self-replicating macros (with Ron Sommeling), about style design (with Andries Lenstra),
I was interviewed about my history with TeX.