Internet resources

Apple II PT3 Vortex Tracker Player: PT3-files player for an Apple II with Mockingboard (with source code) by VMW Software.
AVR-AY – AVR AY-3-8910 Emulator: Resource, dedicated to AY-3-8910 emulator on Atmega8 and player for it.
Leonard Homepage: Arnaud Carre home page. He is YM-format author. There are music of this format, famous ST-Sound emulator for its playing, and also some programming articles on his page.
YM Archive by aldn: Atari ST music archives (alternative to not working ST Sound Plesuredome).
Z80Stealth Emulator Homepage: Official page of Z80Stealth ZX Spectrum emulator by Kirill Kolpakov. This is the best AY/YM emulation today (© Hacker KAY). Emulator allows efficient creating of PSG and EPSG files. Among all of known to me emulators, only Z80Stealth creates PSG files without errors.
Hacker KAY Homepage: Hacker KAY home page. He is original AY/YM emulation algorithm author (used in Z80Stealth). On his page you can find archive of his ZX modules (Russian titles, I translated it to English in Tr_Songs) and AY/YM related data and programs, some MP3 and modules, guest book.
Ironfist Software: Ironfist's projects site. YMEngine is used in some of them.
AY Music Utilities: This is AY music part of World Of Spectrum site.
Project AY: Site is dedicated to .AY-files and .AY-files players and utilities. You can find many techinfo and links about chip music.
RDOSPLAY: Site (saved in web-archive only) is dedicated to OPL2/OPL3 player. There are some AYM and FXM ZX Spectrum tunes can be found on this site. RDOSPLAY documentation contains useful info and formats description. Link to web-archive of the site is found here.
YM2149 Java emulator: Good emulation of YM2149 sound chip is written on Java.
ExoticA! *** Tunes - AY-3-8912_songs *** ExoticA!: ExoticA! site part, on which placed AY-files in native form. Some of them very interested.
AY Player for real Spectrum: Project is dedicated to playing Spectrum music in .AY (ZXAYEMUL) format on real ZX Spectrum. Current version allows play the most of available AY-files with spectrum music inside.
SNDH-files Player Home Page: Big SNDH music archive and SND Player for real Atari ST.
SNDH Atari ST YM2149 collection: All around SNDH: technical documentation, players and the most complete and well sorted SNDH-files archive.
AY/YM Emulation Library: The page is dedicated to Alexander Sashnov's AY/YM Emulation Library with samples like a plug-in for XMMS (Linux's Winamp analog) and console player for playing VTX-files in Linux. The library is based on Roman Scherbakov's (VTX format author) sources.
mR T.A.D. a.k.a. rnR: Site of musician, interested in computer sound and in all my projects.
X-agon's Homepage: AY-musician X-agon's site. Download all his ZX Spectrum music!
AY Riders: International ZX Spectrum music band of Yerzmyey.
YM Rockers: Atari ST music band. Brothers of AY Riders ;)
Lost net the site thematic resources: Nothing lost without trace. You can try to find it in web-archive or in new place.