Wikipedia on the Steel Pan
Wikipedia has good introductory information on the steel pan.
The Steel Pan Instrument
The steel pan, the tuned steel drum, is one of the few genuinely novel acoustic instruments invented in the twentieth century. Its origin is believed to be dustbins, used as rhythm instruments by the traditional Carnival bands of Trinidad & Tobago in the 1930's. During its 50-year history the steel pan has evolved from a multi-pitched percussion instrument to the mellow-sounding melodic-harmonic instrument of today.
Ten facts about the steel drum
Oxford University Press OUPblog lists ten facts about the steel pan and its history.
The Steel Pan - an introduction in Swedish
En kort bakgrund till instrumentet steel pan och karnevalen på Trinidad.
The Rhythm in Steel
A full-length film (1h 15 mins) presenting the story of a retired doctor sailing in the West Indies, who discovers the origins of the steel pan. Contains some interesting information regarding the building of pans and their history.