I do believe this is what you're looking for ;)
http://www.youtube.com/watch?v=kOBtzjS_mvk&t=8 Also, here's a pro-game where they're actually used o.O:
Part 1,
Part 2, or in
original crazy Korean XD
A few people mention StarCraft, but they don't seem to grasp the sacrifices in the game. To elaborate:
Infested Terrans aren't really a sacrifice. They're such a rare occurrence and so finicky to use (notice how, in the game above, one gets dropped right in the mineral line and the probes manage to kill it before it detonates) that sparing gas for them is an indulgence more than anything.
A rather better example of a suicidal unit are the scourge. They are the backbone of Zerg anti-air, what with the rest of the Zerg air being completely outmatched by the other races. Scourge trade efficiently with anything they hit: corsairs, wraiths, even enemy overlords. That alone makes them not a sacrifice - if a unit trades efficiently, it's not sacrificed.
Archons, are generally a way of "recycling" templar that have run out of energy and can not be retreated, or dark templar that stand no chance of sneaking behind enemy lines.
No, the real sacrifices in StarCraft come economically, especially in the early game. Every worker is precious early on, yet you MUST send at least one to scout out your opponent. For Zerg, there is a further sacrifice, by the very nature of the race:
for every structure, you must sacrifice a drone! In the early game, workers are worth their weight in gold, and drones doubly so. Making things worse, the Zerg must use the same production means to make its defensive units. Zerglings can be extremely cost-efficient, but in the beginning, the sacrifice of a potential drone for a pair of lings is tough. This makes scouting especially important, as that information could allow you to squeeze out that precious extra drone.
Later on in a game, there are more tangible examples of sacrifices. To stick with the Zerg, it is standard practice to try and send in squads of lings to the enemy base, offering further intelligence and doing as much damage to their mineral line as possible. These don't come back ;) When mutalisks become available, they serve a similar purpose but with the added benefit of survival. However, once the Terran force moves out onto the field, if the Zerg wants to engage them, he usually has to sacrifice his mutalisks because they are a better tank than zerglings, while the zerglings dish out the DPS and try to flank and surround the enemy medic-marine force. Mutalisks rarely survive this engagement and play no further role in a game.
Lurkers can contain the Terran advance, but when science vessels come into play, there is nothing to be done but retreat. Some lurkers may need to be sacrificed to stall the advance, so that the Zerg can get its defiler tech out. Now, defilers come with Dark Swarm out of the box; the "tech" they need is Consume. Now there's a sacrifice for you! Eat a unit, get energy, cast a swarm! It's a game-changer, especially combined with abundantly available and frightfully upgraded zerglings. However, there are occasions when zerglings are not on hand or die too quickly and a whole expansion is about to fall. What does the defiler consume then? An overlord? A lurker? Another defiler?! It's a tricky question and one that has to be answered in a fraction of a second - defilers are a prime target!
So, that's a little bit of the sacrifice-laden life of a Zerg. The other races? Terrans are not much for sacrifices, maybe float the occasional unneeded building into enemy space to reconnoitre. Vultures perform similar suicidal sorties as zerglings, into enemy mineral lines, but they are so cheap that killing
anything renders them cost-efficient! It's kind of absurd.
Protoss are a slightly different matter. Their units are very expensive and hard to really trade efficiently. When faced with siege tanks and minefields, however, Protoss can use zealots as amazing shock troops. To break a Terran line, the zealots need to rush the minefield, trying to get in close to the siege tanks. Between interfering vultures and the mines themselves, few ever make it. However, the manner of their sacrifice can be quite spectacular. You see, a speed-upgraded zealot can activate a mine and continue on into the tank line. The mine follows. The mine detonates. A zealot has about as much health as a tank, and if it gets a couple of hits in, the tank will die from the detonation too. Other tanks might also decide to target that same zealot, splashing their hapless compatriot. All in all, the zealot dies, but it deals a crapload of collateral damage. Alternatively, the Protoss can just load up four zealots into a shuttle, then drop them onto the tank line. Unless the Terran pre-empts this and takes his nearby tanks out of siege mode, the auto-targeting and splash will kill whatever the zealot drops on. It's referred to as a "zealot bomb" :P
Also, there was the matter of
this particularly epic sacrifice...
