Easy to remember (less accurate but it'll get you there):

1 cup                       250 mL
1 pint                      500 mL
1 quart                       1 L
1 gallon                      4 L

More accurate measurements though they still aren't 100% accurate conversions - however, this is where your personal flair can take over - take the numbers here and slightly modify based on your own needs and tastes.

1 teaspoon                    5 mL
1 tablespoon                 15 mL

1/8 cup                      30 mL
1/4 cup                      60 mL
1/3 cup                      80 mL
1/2 cup                     120 mL
2/3 cup                     160 mL
3/4 cup                     180 mL
1 cup or half a pint        240 mL
1 and a half cups           350 mL
2 cups or one pint          475 mL
3 cups                      700 mL
4 cups or 1 quart           950 mL

4 quarts or 1 gallon        3.8 L