Interpunct / middle dot in American English
In high school, I had one teacher who used it (and insisted that we use it) as a multiplication sign. I have since occasionally seen other people use it that way in mathematics. The reason is to avoid confusion between the multiplication sign × and the letter x. Since x is frequently used to represent an unknown value, there is actually some sense in this. Not a lot, though, since it can also be really difficult to distinguish · from a decimal.