EarTrumpet - Volume Control for Windows
Audio Hero - Over 250,000 royalty free music & sound effects for videos
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
TunePocket - Download 11,000+ royalty free music tracks and sound FX. Buy once, use forever. New music added daily. Save over 50% compared to most popular similar services. Incredible value!
Volumouse - From authors website:
Premiumbeat - Premiumbeat.com provides high quality Royalty Free Music.