An iPod was a music storage and listening device from 21st century Earth.
Owen Harper listened to "Atlas" by Battles on his iPod while cleaning his flat. (TV: A Day in the Death)
In 5,000,000,000, Cassandra presented to fellow guests on Platform One what she identified as an iPod. With it she played Soft Cell's "Tainted Love", a traditional song, and Britney Spears' "Toxic", a ballad from Earth's classical era. (TV: The End of the World)
Other similarly named devices from that era included the iPad and the iPhone. (TV: Dark Water, Kill the Moon)