Most of these numbers have been taken from an old book by Karplus and Porter. To convert from a unit Y in the left hand column to a unit X in the top row, mutiply by the table element, MX,Y. Example:
1 hartree = 27.2107 eV
When accuracy is very important, I recommend going instead to the NIST website: Fundamental Physical Constants from NIST
Energy Conversion Table

hartree eV cm-1 kcal/mol kJ/mol oK J Hz
hartree 1 27.2107 219 474.63 627.503 2 625.5 315 777. 43.60 x 10-19 6.57966 x 10+15
eV 0.0367502 1 8 065.73 23.060 9 96.486 9 11 604.9 1.602 10 x 10-19 2.418 04 x 10+14
cm-1 4.556 33 x 10-6 1.239 81 x 10-4 1 0.002 859 11 0.011 962 7 1.428 79 1.986 30 x 10-23 2.997 93 x 10+10
kcal/mol 0.001 593 62 0.043 363 4 349.757 1 4.18400 503.228 6.95 x 10-21 1.048 54 x 10+13
kJ/mol 0.000 380 88 0.010 364 10 83.593 0.239001 1 120.274 1.66 x 10-21 2.506 07 x 10+12
oK 0.000 003 166 78 0.000 086 170 5 0.695 028 0.001 987 17 0.008 314 35 1 1.380 54 x 10-23 2.083 64 x 10+10
J 2.294 x 10+17 6.241 81 x 10+18 5.034 45 x 10+22 1.44 x 10+20 6.02 x 10+20 7.243 54 x 10+22 1 1.509 30 x 10+33
Hz 1.519 83 x 10-16 4.135 58 x 10-15 3.335 65 x 10-11 9.537 02 x 10-14
4.799 30 x 10-11 6.625 61 x 10-34 1