To promote their 1997 single "Taxloss", the band Mansun hurled £25,000 (approx US$36,000) worth of £5 notes over an unsuspecting crowd of commuters at London's Liverpool Street Station during the morning rush hour. Directed by Roman Coppola, they filmed the resulting chaos and subsequent news coverage and used it as the promo video for the single. All before the age of viral videos and flashmobs!
(The song hasn't really stood the test of time, but it was something of a hit, very much typifying the alt-Britpop sound.)