Links:

http://grayscale.scene.pl - (polish and english) official page of Grayscale, 3 musicians band, you can find there Theta Music Composer and SAP plug-in.

http://atari8.info - (polish and english) polish scene information site

http://jaskier.atari8.info/ - (polish and english) Jaskier home page, author of TMC, best (I think) music composer program for Atari 8-bit

http://atariarea.histeria.pl - (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.