Heavens to Murgatroyd! (from Gilbert and Sullivan's "Ruddigore", via my father.)
and two of my favorite curses:
Thou pig! Thou dog! Thou accursed of Allah! Thou son of a three-legged syphilitic camel!
(for inept drivers:) May your transmission fall out on the Dan Ryan, outbound, on a Friday afternoon! (The Dan Ryan expressway is famous in Chicago for its traffic jams.)
To jaywalkers: You wanna be a hood ornament?!?