Here is a list of all the companies who have participated and helped make freeSFX such a great resource:
Royalty Free Music and Sound Effect Libraries
AudioMicro - a royalty free music and sound effects collection offering instant downloads..
Stockmusic.com is a comprehensive professional library of production music tracks covering many genres and styles including: corporate, sports, rock, dance, romantic, blues, classical, new-age, film scores and much more.
Sound-Ideas.com is home to thousands of professional sound effects within more than 240 collections used in broadcast, post production and multimedia facilities word wide.