Final Fantasy VII

Quick Money:
Go to the desert outside of the Gold Saucer and walk around
for a while. Sooner or later a little Cactus Man will appear. You
can't beat him with magic or weapons, but he can be defeated
by summoning Chocobos or Mogs. If you manage to kill him
he's worth 10,000 gil!

Quick Money II:
At the Gold Saucer most attractions require you to have GP.
Once you have entered by shuttle, go to the top left-hand corner
to the save point. At the house to the right there is a chance that
there will be a dark figure. He will sell you 100 GP for 100 gil...

Lucky 7 fever:
Try to get a character's life to 7777 by Exp. points and switching
Materia around. Once this is done the character will go berserk
and hit the enemy at 7777 points until the battle is over.

Item Duplicator Trick:
You only need the W-Item Materia. During a battle, have the
character with W-item pick a highlighted item that you want to
duplicate. Then pick any other item. When the cursor is over a
character, press "cancel" and your first item will increase to its
original number. Then, press "accept" and then "cancel" over and
over until you have 99 of the item.

Easy 2 Mega-Materia:
In the final dungeon when you are prompted to take your party
to the left and right path... take your party to the right path thus
leaving the rest to go to the left. Follow the path down to the
end where you meet up with the rest of the group. You can take
the path that leads to where the party went left - do it and collect
all the items from the left path. Now return to the group. They
will hand over the items that they found on the left path (which
are the same items you got).

Tetris Elemental:
South of Cosmo Canyon is an island you can barely or maybe
not even see on the world map. But this small little island is
filled with Cactrots. Be sure you have the Morph Materia
equipped along with a weapon with a good attack%. Go to
battle and you will encounter a Cactrot. The Cactrot has 6,000
HP so take off atleast 5,800 to 5,900 damage points, then use
Morph on it. If you don't hit him the first time with Morph then
just keep on trying because most likely you will hit it with Morph.
You now have a Tetris Elemental. Keep on doing this over and over
again and you will get this rare relic.

Slow down the Slots:
In the battle square when the slot machine is going around to
pick your handicap tap Square really fast and the slot will slow
down.

When fighting bosses, combine Final Attack materia and either
Pheonix Summon Materia or a Revive Spell Materia on master
level. If you die you resurrect. Great for Sephroth, Ruby, and
Emerald.

When in the Chocbos Race, hold L1+L2+R1+R2 for extra
speed and hold R1+R2+X to keep speed up and not lose
any stamina.

Against the boss Gi Natakk, all you have to do his give HIM
an X-potion. This automatically drains all of his HP and you win
the battle.