OK, I committed more implementations of sounds to the SVN. Here are the working ones:
Artifact - an artifact is played from hand.
ArtifactCreature - an artifact creature is played from hand.
BlackLand - a land with the B mana ability is played from hand.
BlueLand - a land with the U mana ability is played from hand.
Creature - a creature is played from hand.
Enchantment - an enchantment is played from hand.
Instant - an instant is played from hand.
Sorcery - a sorcery is played from hand.
GreenLand - a land with the G mana ability is played from hand.
OtherLand - a land with no color mana abilities is played from hand.
Planeswalker - a planeswalker is played from hand.
Poison - a player receives a poison counter.
RedLand - a land with the R mana ability is played from hand.
WhiteLand - a land with the W mana ability is played from hand.
The following sounds are added to the enum but are currently not linked to the code because I haven't figured out where they should go (your help is welcome):
Counter - a counter is added/removed (could potentially be split into two different sounds).
Damage - damage is dealt to the creature.
Discard - a card is discarded from hand.
LifeLoss - a player loses life due to damage.
Regen - a regen ability is activated.
Sacrifice - a creature is sacrificed on the battlefield.
Enjoy!
- Agetian