Tali has put her musical spheres and ambient soundtrack generator up on Marketplace.
So it's a shameless commercial - it's also been fascinating for me to see how a real pro goes about it, from the initial idea to the final product, with a lot of cool interludes along the way. (One development session involved hooking up the sound generator to Sauce Sorrowman's chessboard - oh, what the heck, he deserves a plug too - Sauce Sorrowman's chessboard - and hearing the pattern of pieces on the board being transformed into music from the generator. Playing chess... as a musical instrument.)
Anyway. Tali has produced a lot of good stuff, including tools and tutorials available for free from her website... she deserves (at the very least) the feather-light weight of my recommendation added to her products. (Besides, the thing really is totally cool!)