Sounds (from rdpslides.com):
Audio Interchange File Format (*.aiff, *.aif, *.aifc)
Motion Pictures Expert Group Layer-3 (*.mp3, *.m3u) (Note: May only be
inserted with PowerPoint 2000 but may be played back with PowerPoint 97 or
the 32-bit PowerPoint Viewer.)
Musical Instrument Digital Interface (*.midi, *.mid, *.rmi)
Unix Environment (*.au, *.snd)
Microsoft Wave (*.wav)
Microsoft Streaming Format (*.asf, *.asx)
CDAudio (*.cda)