Cal king x Mexican black king (technically a non-hybrid cross):
Variable, but in essence you get kings with less obvious pattern. Many years ago I had one of these. As an adult he was mostly solid brown with some faint dirty yellow bands. Not as cool looking as a Mexican black alone or a Cal king alone.
Cal king x albino Cal king:
Normal-looking Cal kings that are heterozygous for albino (aka het-albinos)
Hybrids/crosses are often a heated subject on these forums. Many folks here are dead-set against the act of creating crosses of any type. Better to go to the hybrid forum to ask questions about such snakes. Here is some mostly unbiased info for you:
Cal king x milksnake (hybrid):
The most common hybrid cross of such is probably Sinaloan milksnake x Cal king. Babies are variable, with some having nearly no red and others having some red. These are never as striking as a Sinaloan alone or a nice black&white Cal alone. You occasionally see them on the classifieds.
Another hybrid you see alot is the "Jurassic king" which is a Cal king x Florida king x Honduran milk to start, with varying proportions of either snake in them. The albinos of this cross can be striking, but many are very plain.
The most commercially successful hybrid may be Cal king x cornsnake. This can produce some really interesting-looking snakes.