[t0mek]

> A music composer that took advantage of the MIDI ports.

Cubase or C-Lab Notator.

> A BASIC interpreting environment.

GFA BASIC.

> A desktop publishing application

This may be Calamus. Interesting fact: "an Atari Desktop Publishing system consisting of an Atari Mega ST computer, mono hi-res monitor, SLM804 printer and desktop publishing software cost less then an IBM or Apple laser printer alone." [1]

http://www.atarimuseum.com/computers/16bits/printers/laser/s...

[aidenn0]

Timeworks Publisher ST was another desktop publishing app for the ST.