Here's a very good Punnett Square Generator...probably the best I've used.
It allows you to represent genes and their alleles with letters of your choice. Just type them in! It will apply the principle of segregation and independent assortment, but you'll have to figure out the phenotypes for yourself using the correct dominance relationship between the alleles.
Try a three trait cross between two Pastel(P) Spider(S) Het Axanthics (n). It would suck to draw that square by hand, but this web tool does it for you.
Unfortunately the results dont paste here correctly....even if you use the tool's print option.