I think the stealth fighter is a serious contestant for the "most useless unit" in civ3. Ranks right up there with the Paratrooper and Explorer. I have removed these from my own favorite mod and replaced it with something more useful. All the stealth fighter is good for is recon, and other units can do that as well, and recon missions are never shot down, so stealth is useless there. IRL, the Air Force has already retired the stealth fighter, lol.
The helicopter is very occasionally useful, if an enemy has a resource on a mountain, you can drop 4 TOW infantry onto it with a couple of helicopters. They will get killed, but this is a useful tactic for attriting the enemy and diverting his forces sometimes. Unfortunately the helicopter seems to be very vulnerable to enemy bombing, however, so use them right away if you choose to at all.