In Traverse Town you can do a little side quest: collecting 10 postcards and put them in the mailbox in the 1st District near the Accessory Shop. You can earn some good items doing this.

Here are the postcard locations:

1. Activate the Blue Trinity mark in front of the cave in the 1st District.

2. Open the Blue Safe behind the counter were Cid stands (Gummi Shop) in the 1st District. 

3. Open the chest on top of the awning of the "Boots & Shoes" shop in the 2nd District. You need High Jump to get there.

4. Attack the fan in the Item Shop in the 1st District.

5. Open the chest on top of the Accessories Shop in the 1st District. You need High Jump to get it.

6. Visit Gepetto's House in the 1st District after you completed Monstro. Examine the pot at the left corner.

7. and 8. Cast Thunder on the cords that are sticking out in the 3rd District. Then enter the Gizmo Shop (2nd District) and use the moving platforms to step on the 3 square buttons. After that examine the clock for the 2 postcards.

9. Jump on the furnace in the Accessory Shop in the 1st District and examine the sign board on the wall.

10. Go into the Gizmo Shop after defeating Guard Armor. Enter the north door to get at the back of the shop. Then climb the ladder and jump onto the houses until you reach a hole that leads to the 3rd District. Check the platform to get the Final Card!