General Music + Sound Editors

FL Studio

FL Studio Tutorials

Audacity 

Audacity Tutorials

Jellynote (Learning Tool)
LMMS

Musical Programming Languages

Chuck=>

 

Chiptune Synthesizers 

Pulseboy

Midi Sequencer

Jazz++

Sound Effects (SFX) Creator

Bfxr 

Pre-made Music and Sounds

Sound Rangers (Store)
AudioMicro (Royalty Free)
Bensound (Royalty Free)
Audiopad (Varies)
Incompetech
Open Soundtracks