Secret Developer's Room (Final Fantasy IV):

The "Secret Developer's Room" is hidden in the Dwarf Castle in the Underworld. Between the weapon and armor shop is an odd section of wall that is actually a doorway to the "Rally-Ho" pub. On the right side of the pub is a fake wall. Walk through this wall and you will reach a staircase which leads to the Secret Programmer's Room.

Skip Sealed Cave event (Final Fantasy IV):

When you go to the Underworld and go to the Dwarf Kingdom, after you have to fight the dolls in the secret crystal chamber, Rydia returns and helps you fight. After you are done and back in the main chamber, use her warp spell to get back to the crystal room. The crystal will still be there. Approach and examine the crystal to take it. Later when you have to go to the Sealed Cave, if you have the Crystal, you will not have to enter it. You can skip that event and the game will automatically go to the sequence that normally happens as you are coming out.

Double Weapons and Shields for Free:

During a battle select the items menu on the character you wish to double something with then select an empty slot in your items inventory and press up until you see the left and right hand equip screen and select an item. Repeat for both items then when you exit the battle select equip and equip the item you just took off and you should see it say dark sword 2. As an example on the same hand then unequip the weapon and equip it again and you should have one equipped and one in your items inventory. Repeat if necessary and sell for big bucks.

Experience (On FF IV):

In the Tower Babel Overworld after you get an edge and are on your way to fight Rubicant if you run into a sorcerer and two blade men kill the two blade men but leave the sorcerer alone it will summon more monsters and so on and so on, after a while the more monsters you kill the more experience you will get at the end of the battle so far I have gotten 20,000+ exp points in one battle thats handy when you need to level up it will probaly work through out the game were there is a monster that summons others i just mentioned this because it was very easy.

Sylph Summon (OnFF IV):

To get the Sylph summon, you need to have access to both worlds. First, you have to be past the part where Yang saves you from the cannons. Then go to the Sylvan Cave in the Underworld. Talk to all the Sylphs and Yang. Then when Cid attaches the drill to the Enterprise, go to the overworld. Go to Fabual and talk to Yang's wife 2 or 3 times. Then she will give you "Sylph." Afterward go the Sylvan Cave again and talk to the Sylphs once more. Then you will have access to the Sylph summon.

How to Beat Ashura and get Bahamut's Summon (FFIV):

Ashura: Before the fight get Rydia's defence up a lot so that Aahra's attacks only do around 300 to her. Then make sure Rosa has the wall magic (I think she learns it around level 35). Cast wall on Ashura , and all her cure spells go to you and if Rydia is killed don't revive her , let Ashura's life do it.

Bahamut:

In the Lunar castle if you wander around a lot you will find a place with people in it. Talk to the one at the top of the cliff, he is Bahamut. After the fight starts cast "Wall" on all of your party members. When he uses Mega Nuke or Mega Flare (I forgot which) it will bounce off your whole party. After you beat him he will become the best summon that does damage you will ever get.

Fight Lavos Early:(Chrono Trigger)

To fight the last boss Lavos early in the game and get a new ending then you start a new game + file and when you get back from 600A.D. and you have to "Escort" Marle home don't. Instead, examine the shining dot on the right telepod that Lucca created NOTE: THIS CAN ONLY BE DONE ON A NEW GAME+ FILE.

Patience Comes to Those Who Wait:

When you approach the magic chests and examine them, it says that the chest will react to the pendant and it will ask you to examine it, choose no, then go to the next time period over. Then go to the same box, and it will have a stronger item than the time before. Example: if you go to the Hero's grave in 600 a.d. in a chamber with stairs, have the chests react to the pendant but DO NOT examine its contents. Now transport to 1000 a.d., go back to Hero’s grave, and examine the same chests, now you will have the valkreye in one of the chests, which is Marle's ultimate weapon. This goes the same for the nova armor as well, if you would do not check its contents, it will become Moon Armor, which gives max def!

Easy Exp. & Tech Points:

On the way to reviving Chrono on Death Peak, there is a place where enemies will roll by you (after the 2nd Lavos Spawn). Make Magus have a gold stud and cast Lighting 2 on the group after youy touch them. Each group is worth 48 tech points and 2000+ exp points. Leave and come back for more!

Ending 8:The Oath: (Chrono Trigger)

To get this ending use the bucket at the End of Time right after delivering the complete Masamune to Frog in the Cursed Woods and defeat Lavos. In this ending Frog goes to Magus's alone to defeat Magus and break his curse. FROG LOOKS COOLER THAN CRONO WHEN HIS CURSE OF BEING A FROG IS BROKEN! EXTRA FEATURES UNLOCKED: MUSIC TRACKS 51-60.

Fight Lavos Earlier:

Once at the end of time examine the bucket at the upper right to fight Lavos. You will get ending#4(talk to Spekkio and do what he says first).