Nice work on the unpacker Daekan... it looks so clean and elegant coded up in Python
I took a quick look at some of the audio files in SndAmb1.vpk and noticed that they aren't usable WAV files as-is... however... they are very close.
For whatever reason, SOE deviated ever-so-slightly from the .WAV standard (yet still chose to call them .wav files... sigh)... so all you have to do to listen to the files in WinAmp is make a quick change to the header.
Open up the file you want to listen to in a hex editor and overwrite the first 4 bytes with the ASCII characters 'RIFF' (hex: 52 49 46 46) then insert three null bytes (00 00 00) and then overwrite the next byte with 00. Save the modified file, and you'll be able to listen to it with Winamp. Its a quick and dirty hack, but it does the job.
I poked around some of the other files and it looks like (pretty obviously), .sp files are used to describe shaders for objects, .hit files are used to describe simplified meshes to be used for the purpose of collision detection and .draw files are used to describe the mesh to be rendered.
.voc files appear to contain quite a bit of plaintext information about various objects (haven't really looked at what yet) and .lut files seem to be collections of .voc files in the format: a single null byte followed by a list of .voc files in the following format: unsigned short describing the length of the filename, the filename (in unsigned chars, of course) followed by 16 bytes of unknown function. Rinse, repeat.
I hope thats useful to someone.