I've made some new grenade boundce sounds.
You can get them at:
http://excalibur.nvg.ntnu.no/nexuiz/pk3 ... -08-20.pk3
Just put the pk3 file in the nexuiz/data dir and you should be good to go.
there is 6 sounds in the pack, 2.0 only uses the first 3 of these. If you unpack and rename the files you can choose any combination as the three you want. I am hoping to get this into the next nex version, if so, all 6 sounds should be used.
Edit:
These are made from absolute scratch, so they can easily be used and disted without any problems with licencing.