Here is a list of all topics with brief descriptions:

GBA: Initialization/Main Functions
GBA: Module Playback
GBA: Sound Effects
GBA: Playback events
GBA: Misc definitions / reference
NDS: ARM7 Initialization/Main Functions
NDS: ARM7 Module Playback
NDS: ARM7 Sound Effects
NDS: ARM7 Streaming
NDS: ARM7 Reverb
NDS: ARM7 Playback events
NDS: ARM7 Misc definitions / reference
NDS: ARM9 Initialization/Main Functions
NDS: ARM9 Module Playback
NDS: ARM9 Sound Effects
NDS: ARM9 Streaming
NDS: ARM9 Reverb
NDS: ARM9 Playback events
Maxmod Definitions and Types