My contribution
This is just a brief list of the ST demos written by Delta Force, Offbeat and The Hijackers in which I (Flix) was involved in. I will soon add a download link to all these demos.

THI Demo Preview
THI Demo Preview (THI, 1988)
Mega Musix Demo
Mega Musix Demo (THI, 1988)
Gigastars Demo
Gigastars Demo (Offbeat, 1989)
Illumination Demo
Illumination Demo (Offbeat, 1989)
Illumination Demo 2
Illumination Demo 2 (Offbeat, 1989)
Illumination Demo 3
Illumination Demo 3 (Offbeat, 1990)
Module Collection Disk 1-10
Module Collection Disk 1-10 (Offbeat, 1990)
Offbeat Demo Collection Vol. 1
Offbeat Demo Collection Vol. 1 (Offbeat, 1990)
The Musical Wonder 1990
The Musical Wonder 1990 (Offbeat, 1990)
The Musical Wonder 1991
The Musical Wonder 1991 (Offbeat, 1991)
Poppycock Demo
Poppycock Demo (Offbeat, 1992)
Alfons' Greatest Samples Part I
Alfons' Greatest Samples Part I (Delta Force, 1992)
Alfons' Greatest Samples Part II
Alfons' Greatest Samples Part II (Delta Force, 1992)
Alfons' Greatest Samples Part III
Alfons' Greatest Samples Part III (Delta Force, 1992)
Punish Your Machine
Punish Your Machine (Delta Force, 1992)
Atari Fair Demo '92
Atari Fair Demo '92 (Delta Force, 1992)
Alfons' Greatest Samples Part IV
Alfons' Greatest Samples Part IV (Delta Force, 1993)
Offbeat