Today’s featured promo on MacUpdate offers PolyPhontics GB 1.2.1 for US$14.95 (40% off, retail $24.99). “PolyPhontics GB is a software instrument toolbox made specifically for Apple’s GarageBand. Sporting some of the same features as its big brother, PolyPhontics, PolyPhontics GB gives you the tools you need to create software instruments for use in GarageBand compositions.” PolyPhontics GB requires Mac OS X 10.3 or later and GarageBand.