heres a site i go to to get a general idea of a coins worth.
http://www.sammler.com/main.htm
as far as some key dates;
indian head cents-1864L,1869 (8 over9),1877,1888 over 7,1908S and 1909S
lincoln cents- 1909SVDB,1914D,1922 plain, 1931S,1955 double die and 1972 double die
buffalo nickels-1913D(variety 2),1913S (variety 2),1916D double die,1918D (8 0ver 7),1937D three legged
jefferson nickels-1943P (3 over 2),1949D (D over S)
barber dimes-1895,1895O,1896O,1896S,1897O,1901S
mercury dimes-1916D,1921,1921D,1942 (2 over 1),1942D (2 over 1)
roosevelt dimes- none in particular
barber quarters-1896S,1901S,1913S
standing liberty quarters-1916,1923S
washington quarters-1932D,1932S,1943S (double die obverse)
barber half dollars-1892O,1892S,1893S,1897S
walking liberty halves-1916S,1921,1921D,1938D