The Infi-Map is a complete map of the locations of all natural and man-made ghost portals into and out of the Ghost Zone--as well as serve as an address book/map "for a bazillion ghosts". The map also changes as the ghost zone changes. The map itself resembles a scroll.
It makes its first appearance in the episode "Infinite Realms" when Frostbite offers to let Danny and his friends use it to lead them home. Apart from being a complete map of the Ghost Zone, the map has the unique ability to transport its user(s) to any specific portal or location on the map. The map activates itself when the user(s) say where it is they want to go to, but sometimes the map takes the user(s) not where they want to go, but rather where they need to go. The Infi-map also has an amazing ability of "opening" a portal when the user wants to go to a certain location or time, whether when or where or Ghost Zone or Earth (an ability similar to Clockwork's teleportation, though the Infi-map seems to be more limited in doing so). The Infi-map will immediately "fly" to the portal while the user(s) hang on to one end of the map. It's important to never stray from the maps path or you'll be lost forever. At the end of the episode, the map goes back to the care of Frostbite and his race.
In "Phantom Planet", Vlad Plasmius steals the Map from Frostbite and uses it to instantaneously travel to the rings of Saturn and his satellite there. It is retrieved by Danny, Sam and Tucker for Frostbite and is later used to help track down ghosts to help him save the planet from the "disasteroid".