DiceRoller

Dice Roller is a handy application for rolling dice for many applications. Roll up to 6 dice, with options for number of sides and /- modifier for each die and get a total for each die and a combined total for all dice rolled.

Also has the options for several global modifiers, such as drop lowest roll, or adding to highest roll. Best of all, you can save presets for common dice rolls for later use.