AudioRackSuite is an audio player system intended for use in live-assist and automated radio. AudioRack contains a "rack" of five players which can be loaded with audio files and controlled manually, or loaded and segued automatically under program control from a playlist (radio segues, not the iTunes style fades).
AudioRack has extensive AppleScript support which allows it to run unattended. AudioRack is also a database front end for MySQL which can be used to organize, find and manage the audio files that it plays. AudioRack requires access to MySQL in order to run -- however you can play audio files that are not in the database library without the files being automatically added to the library (as iTunes does).
Finally, AudioRack has a separate audio playback engine (called arplayer) that does the grunt work of playing the files (any file that QuickTime will play) using a 10 second long ring buffer and Apple's CoreAudio system. Unless your computer is really hung up, it won't glitch - even with sluggish networked audio files. As long as the network can maintain the encoded bit rate of the file over ten seconds, it won't glitch. This does not use QuickTime's built-in (yuck) player! Did I mention that it is also an Open Source program so you are free to add, improve, and customize it?