Wikipedia has an interesting little list:

* 4 ft 8 1⁄2 in (1,435 mm) – 1825 – chosen by George Stephenson
* 5 ft (1,524 mm) – 1827 – chosen by Horatio Allen for the South Carolina Canal and Rail Road Company
* 1 ft 11 1⁄2 in (597 mm) – 1836 – chosen by Henry Archer for the Festiniog Railway to easily navigate mountainous terrain (started Britain's first narrow gauge passenger service in 1865) (originally horse-drawn)
* 7 ft 1⁄4 in (2,140 mm) – 1838 – chosen by I. K. Brunel
* 5 ft (1,524 mm) – 1842 – chosen by George Washington Whistler for the Moscow – Saint Petersburg Railway based on Southern US practice
* 5 ft 3 in (1,600 mm) – 1846 – chosen in Ireland as a compromise
* 5 ft 6 in (1,676 mm) – 1853 – chosen by Lord Dalhousie in India following Scottish practice
* 3 ft 6 in (1,067 mm) – 1862 – chosen by Carl Pihl for the Rψros Line in Norway to reduce costs
* 3 ft 6 in (1,067 mm) – 1865 – chosen by Abraham Fitzgibbon for the Queensland Railways to reduce costs
* 3 ft (914 mm) – 1870 – chosen by William Jackson Palmer for the Denver & Rio Grande Railway to reduce costs (inspired by the Festiniog Railway)
* 2 ft (610 mm) – 1877 – chosen by George E. Mansfield for the Billerica and Bedford Railroad to reduce costs (inspired by the Festiniog Railway)
* 2 ft 6 in (762 mm) – 1887 – chosen by Everard Calthrop to reduce costs; had designs for a matching fleet of rolling stock