25. Once (2006)
Made for less than $200,000, this scruffy indie from writer-director John Carney redefines the musical form. It stars an actual musician Glen Hansard, of the Irish rock band the Frames as a fictional busker who falls for a quirky pianist (Marketa Irglova) on the streets of Dublin. They have a tortured romantic flirtation, and pour their hearts out to each other in mournful original tunes that feel utterly real because they're not played as musical fantasy. A must.
With ''Fame'' dancing into theaters on Friday, our list of ultimate ''all singing! all dancing!'' cinematic extravaganzas, from ''South Park'' and ''A Hard Day's Night'' to ''Singin' in the Rain,'' ''West Side Story,'' and our No. 1