Aircraft vs Tigers:
The YAK-9T 37mm gun rarely works on a Tiger's turret, but it's worth a try if you're desperate. Likewise the 110G2's 30 and 20's don't do a whole lot, but once in a blue moon they yield results. Anything less than cannon however is hardly ever more than an annoyance to the Tiger. 500lb or 1000lb bombs do work against tigers when they're spot on. I've lost about 30 tigers to well placed bombs, but do not discount the 7.7mm turret pintle gun. Even a heavily armored IL-2 is modeled to take damage from it, and I've killed more than one with the pintle peashooter. If your're getting plinked to hell, either approach from the turret's rear left or at a sufficiently steep angle, and the gun won't be able reach you.
GV's vs Tigers:
Usually you can ambush a tiger by hiding and listening for its distinctive engine sound, so turn off your freaking engine and listen. Also, Smoke is an excellent aid to hunting tigers, but the hunting is best done in groups of panzers that coordinate angles of attack. Smoke however has it's problems because one or two rounds does not completely obscure the target's vision. Lay it on thick, or use it as a distraction so that someone else can flank the tiger. Also, for God's sake use AP ammo. HE is going to bounce off a tiger unless you're in another tiger at close range. Even then you'd have to hit his turret or treads to so much as cripple him.
Panzers have tough times with tigers, but there are weaknesses. Though nearly invulnerable to panzers from the front, a shot on the ventral side of the hull between the tracks will sometimes kill a tiger--especially at close range (see 'Why You Shouldn't Bring a Tiger Into Trinity's Center City'
). The safest bet when killing a tiger is to go for it's turret to disarm the thing. Place every shot you can take on the turret if you are at a reasonable range. If you're stuck at D1500+ well, the tiger has a distinct advantage in a standoff fight, so don't hope for much, and just keep trying to get shots on his rear or broadside. Get close if you can.
Osties have virtually no chance against a tiger. However, once I killed a tiger by catching him descending a hill and plinking him on TOP of the turret about 70 or 100 times. Tigers are field tanks and cannot raise or lower their main gun very far. So when the poor bugger was on the hill, he couldn't get a shot at me while I was drilling him. I imagine that if roles were reversed, the tactic would work so long as the tiger was too close to the hill I was on to elevate his gun. (i.e. he blundered too close, or I jumped him) As far as wounding a tiger goes... an ostie ha a good chance at destroying a tiger's treads provided you actually hit the tread and not the skirt armor. Also, if the tiger is damnfool enough to drive into you, there is no collision, and your 37mm will kill his turret in one or two shots while your muzzle is inside the turret. This is not at all realistic, and it's not a tactic I prefer. In fact, I think that tigers should be able to ram other gv's to great effect instead of slipping through like a Hogwarts ghost.
M8's are at a terrible disadvantage against a tiger. Their only hope is to hit the tiger's turret repeatedly while it is distracted. The turret is really only vulnerable from multiple hits perpendicular to the side or rear. Chances are you're gonna buy it if you run into a tiger unless you can weave in and out of buildings in a city.
Good luck. Hope you catch the tiger by it's tail.