Maybe they r playing tournaments and are using push / fold charts? I wouldn't advise anyone playing cash games to use preflop charts, unless he is complete begginer. I never used charts, but i know that in program equilab (its like pokerstove) there are many predefined hand range charts.

ICM can be a good reference, but tough to use in play. I sometimes review hands I play with ICm to get a guideline for my preflop play. However, I wouldn't recommend relying heavily on such charts, because there are much more variables to preflop play other than position, chip stacks and blinds/antes.

Here's a link that could help you.

ICM/Nash Calculator.

Ty! Regards