(polish and english) official page of Grayscale, 3 musicians band, you can find there
Theta Music Composer and SAP plug-in.
(polish and english) polish scene information site
(polish and english) Jaskier home page, author of TMC, best (I think) music composer program for Atari 8-bit
(polish only) another great site about polish scene
http://atariarea.histeria.pl/PLus/index_pl.htm - (polish only) official page of (I think) best
Atari xl/xe emulator for Windows.