Chocobo Racing
There are lots of great items to obtain at the Chocobo Races. Most of them are only available to those lucky enough to pick a winner in an S-class race. This class isn't abailable to just anyone; you won't get the chance to try it until you've become a full-blown Chocobo jockey.
Picking a winnner isn't easy. You must factor in each Chocobo's top speed, stamina, attitude, and the skill of the jockey. Stamina seems to be a most important attribute, but a poor jockey can run even teh best Chocobo into the group. You should wait until you actually participate in Chocobo races before trying to get the really good items. Otherwise, you'll end up spending a lot of Gil that could instead be used to breed your own championship-quality Chocobo.