I thought I'd share a list Rick Snow is compiling with the help of a few collectors. Currently, they've gathered 88 varities; I'll post the complete list when it's done.

Note: the S-numbers refer to Rick Snow's numbering system for FE/IHC varieties.
1856 S-1
1857 S1
1857 S3
1857 S4
1857 S7
1857 S8
1857 S9
1857 S11
1857 S16
1858/7 LL S1
1858/7 LL S7
1858 SL S2
1859 S1
1859 S2
1859 S3
1859 S6
1861 S1
1862 S2
1862 S4
1863 S5
1863 S10
1864 No L S4
1864 No L S11
1864-L S1
1864-L S2
1864-L S3
1864-L S4
1864-L S5
1864-L S7
1865 P5 S1
1865 P5 S2
1865 P5 S3
1865 F5 S1
1865 F5 S2
1865 F5 S14
1866 S1
1866 S2
1866 S3
1866 S4
1867 S1
1867 S4
1867 S5
1867 S8
1868 S1
1869 S1
1869 S3
1870 S5
1870 S8
1870 Pick-Axe Shallow N Rev. S7
1870 Pick-Axe Bold N / Shallow N Rev. S17, S18, S27
1870 Pick-Axe Bold N Rev. S41
1870 S18
1870 S19
1870 S20
1870 S21
1871 S2
1871 S4
1871 S5
1872 S10
1873 Cl 3 S1
1873 Cl3 S2
1873 Op 3 S1 (runner-up variety of whole series)
1874 S1
1875 S1
1878 S1
1880 S1
1882 S6
1883 S1
1883 S6
1883 S7
1883 S8
1886 T1 S1
1886 T1 S4
1887 S1
1888/7 S1 (the top variety of whole series)
1888 S2
1889 S1
1889 S3
1889 S4
1889 S31
1890 S1
1890 S3
1891 S1
1891 S7
1893 S6
1894 S1
1894 S2
1897 S1
1897 S3
1907 S1
1907 S2
1907 S3
1907 S7
up to 88.