I can't really be more presice now
I can.
[small](some of these actually may already exist, as there's a few I'm not sure about, but will throw in anyway, to be safe)[/small]
- Resource is low (defined in the resource XML to allow sounds to be tailored to each resource)
- Unit's health is low (meant more for hero units, etc, and specified with a timer)
- Morph completed
- Upgrade completed
- Building built
- Production complete (specified on the unit tag, so can be tweaked for each unit and each produce command, eg, "Production of Swordman completed at Barracks.")
- Command queue emptied
- Cancel sound (as in, clicking the cancel button to stop a command)
- Building on fire (that could be fun - provided you could hear the rest of the game over the screaming)
- Player defeated (likewise - defined in the faction XML)
- Enemy sighted
- Offscreen attack (don't think you can specify a sound for it in MG yet? - recommended GAE's syntax for compatibility)
- Beginning upgrade/produce/morph/build command (play as the upgrade/morph/produce/build starts in the queue, so when you click the button to produce a Swordman, you might hear "Production of a swordman commenced.", etc)
- Beginning of new skill sound (play one sound before executing a type of command, and don't play it again until a new command has been commenced inbetween. eg, if on an attack command, the unit might give a battle roar before attacking, but won't do it again until done attacking. If it moves to attack a new unit, it would give that cry again, etc)
Yeah, some of these could be difficult to implement, or impractical. Mostly meant as a comprehensive list of possibilities, and who knows, some mods may be able to really make use of some of them (commercial games often have thousands of sound effects these days).