I get that corellation is the covariance divided by the multiplie variance of the two, uh, things.
What i don't get is why they are divided by the multiplied variance, and why that limits the value to the range -1 : 1.
I suppose i'm really looking for a logical explanation, although a mathematical one wold welcome nontheless.
As Michael said, the fact that the correlation coefficient is between $-1$ and $1$ can be shown as a special case of the Cauchy-Schwarz inequality (see https://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality#Rn ).
There is a geometrical interpretation where you see random variables as vectors. Then the covariance is a scalar product, the standard deviations are the norms and the correlation coefficient is the cosine of the angle between the random variables.
But you can also see this as a scaling. Dividing by the standard deviations is a way to put everything on the same scale, so that you can compare variables that have different units for example.