In Ocarina of Time there is one main side quest. It's a long long chain of item trading. Get item A bring it to person A and he'll trade you for item B. It continues on until you get the legendary Biggoron Sword. The quest is livened up by interesting items and time limits. Whenever a time limit occurs, never use a warp song, because the timer will automatically hit 0.
Pocket Egg
Talk to Anju (the lady allergic to chickens) as an adult. She will give you the pocket egg to take care of. Wait a day for it to hatch or just play the Sun's Song a couple times until it hatches into a Pocket Cucco.
Pocket Cucco
Take the Pocket Cucco to Talon (the nice guy from the ranch) he should be sleeping in one of the buildings in Kakariko village. Pull out the Pocket Cucco and it will crow and wake him up. He'll run off to Lon Lon ranch if you've obtained Epona. Take the Cucco back to Anju and she'll trade it for Cojiro, a rare blue chicken.
Cojiro
Take the Cojiro to the slumped over man in the lost woods. He will trade the Cojiro for an Odd Mushroom. The Odd Mushroom will spoil, so hurry to Kakariko Village.
Odd Mushroom
Take the Odd Mushroom to the old woman in the blue potion shop in Kakariko Village within two minutes. DON'T WARP! She will use it to create Odd Medicine. If you don't make it, you'll end up back in the Lost Woods and have to trade Cojiro again. The best way to get back to Kakariko Village is through the entrance into the Goron City in the Lost Woods. From there, run down the mountain into the Village. Just past the gate into the Village, there's a house with a blue roof above you. You can get on top of that roof with the hookshot if you position yourself just right. Do so, then jump down and run up the stairs to the door of the house with the red roof. Talk to the old woman inside to trade the mushroom.
Odd Medicine
Return to the place where you traded Cojiro. Fado, one of the Koriki girls, will be there instead. She says the man left to avoid turning into a Stalfos. She takes the potion but gives you the Poacher's Saw he left behind.
Poacher's Saw
Go to the carpenter's tent in Gerudo Valley and trade this to the boss of the carpenters. He will be shocked to see it since he hasn't ever since he left it with his wife. He'll give you a Broken Goron's Sword in return.
Broken Goron's Sword
Take this up to the Biggoron on top of Death Mountain. He will trade the broken sword for a prescription. His eyes have been blinded by a recent eruption on the mountain, and he can't work on the sword.
Prescription
Take the prescription to King Zora (be sure to unfreeze him first). The king will take the prescription and tell you he doesn't have the medicine but does have the ingredients for it and give you a perishable Eyeball Frog . He will tell you to give it to the scientist in Lake Hylia. If you don't make it, you will automatically go back to Zora's domain and must make the Prescription transaction again.
Eyeball Frog
You must give the frog to the professor in Lake Hylia in three minutes. DO NOT WARP THERE, your clock will go down to one second left if you warp. If you can get it to the professor in time, he'll mistake it for his dinner, then make you the World's Finest Eyedrops. However, there are no preservatives in it, so it will spoil. If you don't make it, you automatically go back to Zora's domain and must make the Prescription and the Eyeball Frog trades again. The best way to do this is to exit Zora's Domain and dive down to the shortcut to the Lost Woods. Exit the Woods and then the Kokiri Forest into Hyrule Field. Call Epona if you have her (if you don't, use your map to aim at Lake Hylia, turn 180 degrees, hold down the Z trigger, and run backwards to the Lake. It's faster than running forward). Once you get to Lake Hylia, go to the house and talk to the professor.
Eyedrops
Now you must get back to the Biggoron within four minutes, again DO NOT WARP! When you give him the Eyedrops, he uses them gives you a Claim Check to claim the sword because it will take three days to fix the broken sword.
Claim Check
Either sit around patiently for three days or play the Sun's Song six times and talk to Biggoron again. When you do, you get the Biggoron's Sword from him.
Biggoron's Sword
Probably the sweetest blade this game has to offer, the Biggoron's Sword itself is twice as powerful as the Master Sword. It takes two hands to wield just like the Giant's Knife, but this one doesn't break on you.