OS: Linux (Mepis 8, Linux Mint 7, or Ubuntu 8.10)
Graphics card: NVidia FX5200 (?)
Nexuiz: Version 2.5.2, SDL, 686

The "tink" sound (the sound you hear when you hit another player) is absent.

cl_sound_tink1 is the default weapons/tink1.wav (but I can't find this file). All Audio effects are turned on including the Hit Indicator, and I've tried various combinations of turning effects on and off. Still no tink. The audio is also set to two channels at 44.1kHz (the only frequency that works).

I can run this with any of the versions of linux listed, and the same thing happens.

Maybe my aim is no good...

The sound file responsible for that sound is in the data20090403.pk3 file
Sound\misc\hit.wav

You could try a work around by adding a sound directory under the data folder
then create a misc directory under sound
then put an alternative hit.wav in that folder