Electric Butterfly announced the immediate availability of Stimulus 4 for the Mac on Tuesday. Stimulus is a media browser that lets you view and organize the music, photos and videos on your Mac through one interface. The new version includes improved support for Mac OS X 10.4, a redesigned interface, improved file organization features, adds support for AAC, AudioBook , and MP4 video files, and more. Stimulus 4 is available for download at the Electric Butterfly Web site, and is priced at US$19.95. The update is free to all Stimulus customers.