Horse shoes are only lucky if the ends are pointed up. If they're pointing down the luck pours out.
Four leaf clovers.
Caowyth makes a good point though in that good luck symbols can be very personal. A person can have a lucky penny, troll doll, rock, pair of underwear etc. I used to have a Magic Square I carried to ward of wolf attacks. Its magic must have been really strong since even though I lost the square I've never been attacked by a wolf.
A four leaf clover
A bird pooing on you
7 of anything coming at once
A naked woman at the helm of a ship
Your clothes being caught on a bush
A new moon
Sneezing 3 times before breakfast
Your hair being cut during a storm
Sleeping on unironed sheets
Carrying an acorn in your pocket
Whistleing in the dark
Finding a penny and picking it up
Carrying a rabbit's foot.
Putting on your clothes inside out
Picking up a pin
Seeing Bats flying overhead at nightfall
Walking in the rain
A black cat crossing your path
Breaking a mirror
A horse sweating
Walking under ladders
Dropping a knife and picking it up
Giving an empty purse
Putting a hat on the bed
Taking off your wedding ring
Seeing an owl during the day
Opening an umbrella indoors
Killing a seagull
Bread not rising
Killing a cricket
Putting your left foot on the floor first up when you get out of bed
Putting shoes on a table
I know that statues of elephants are lucky if the trunk is pointed upwards. Other that that, all I know has been covered.
Vaughn on Alias said that spiders were lucky once...I didn't see that one on the list
(This is off-topic but not...My RPG group had a set of stuffed goslings that we would pat on our dice before a roll, because one night we used one as a stand-in for an absent player, and it rolled a natural 20. Only that one was lucky, though.)