Using punnett squares to express sex/gene linkage and recombination frequency
The Punnett squares are a general way to visualize the product of any two polynomials; for example, you know that the result of (a + b)(c + d) is the sum of the four terms ab, ac, bc, bd. You may put it this way:
  | a   b
----------
c | ac  bc
d | ad  bd

Suppose that the female sex gametes are of two types, X1 and X2, which are transmitted with probabilities 0.9 and 0.1; suppose that males form three types of gametes, X1, X2, and Y, with probabilities 0.45, 0.05 and 0.5. Then, you may visualize the outcome of a general population mating this way:
    |Fem   X1   X2
    |      .9  .1
--------------------
Male|
X1  |     X1X1  X1X2
.45 |     .405  .045
    |
X2  |     X1X2  X2X2
.05 |     .045  .005
    |
Y   |     X1 Y  X2 Y
.5  |     .45   .05

(You may note that this situation roughly depicts the population genetics of color blindness)