Dragonball Comedy
These items are of a magical nature so its difficult to class them and to be totally sure of their power.
Taipons Orcarina - Taipon is one of the guardians of the Hildegarde monster. His flute/orcarina was at one point the only thing that could paralyse or stop Hildergarde. There is only one tune that could halt Hildergarde and as far as i remember
Pottarra Earrings - The Kaioshins all have a pair of these. When 2 people where one on either ear, they fuse permanantly to become a new entity. Goku and Dad did this against Maijin Buu when it seemed like there was no other option. Lucky for them, when they got absorbed by him, they were able to split up.
Nimbus - Nimbus is the cloud that Goku used to fly around on until he learned how to fly quicker than Nimbus. To use it you have to have a pure heart.
Mr Popo's Magic Carpet - Mr Popo has a magic carpet which can take people places.