I know loke (the guy that develops HAM) has sounds in his matchviewer, perhaps he is willing to release those under somesort of free licence?
Could be worth looking into. I know most Swedish people would prefer using the jingle that the national radio uses for it's sport transmissions when there's been a goal. :-)
Btw, I've checked in event notification and sound support now. It seems to work (as I can tell of watching games for 20 minutes).
Note that it is turned off by default, so you have to activate it in the settings.
/Oscar