Kamikaze is a term used for anything that is used as a suicidal weapon. Usually they are cheap, lightly armoured, deal a large amount of damage, and are best used in large groups. Two units in Supreme Commander and Supreme Commander: Forged Alliance that are kamikaze style are the Cybran Fire Beetle and the Aeon Mercy. They are lightly armoured, the Fire Beetle with 750 Health and the Mercy with 10, and they both explode upon impact with the target, dealing high damage.
Because of its devastating air crash (15,000 damage) and the ease of destroying it with ground AA emplacements or large numbers of ASFs, the Aeon CZAR is often considered a kamikaze unit, as it can destroy a huge area of an enemy base by flying over it and being shot down on top of it. The high-powered Quantum Beam Generator will also inflict a large amount of damage while the CZAR lives as well. However, this is not terribly cost effective unless it results in a commander kill, especially as the enemy gets to harvest the hulk for an incredible amount of mass to rebuild with.
The Cybran Soul Ripper also has a powerful air crash, but because of its firepower and health, the Soul Ripper is best used either as its primary role as a gunship or used as cannon fodder while non-experimental units attack other parts of the base. The Seraphim Ythotha is another unit that devastates when it dies, but because of its low health, high fire-power, extreme price, and the ability to destroy your own units when it dies (Othuy Unidentified Quantum being), it is better just to keep it alive.