http://iansvivarium.com/punnett/
The link will take you to a calculator that can be used for any species. IMO it is one of the better ones around because it can handle a problem with up to 4 different alleles in a given locus (2 alleles for the male and 2 entirely different alleles in the female). Most of the others can't handle more than a few species or more than 2 alleles per locus. That site also has a morph calculator for corn snakes.