Note: This is mainly for USA.
For academic positions (tenure-track, visiting, postdoc, non-tenure track etc), UFL stats and Washington stats departments keep an up to date tab on the job postings. These are also free to post on I think. This is the general go-to for most people looking for jobs I know.
The AMSTAT website has a job list, which I believe you have to pay for to post there.
A lot of the applications are processed through MathJobs, so that is another good place to advertise. I am not sure it that costs any money.
As a graduate student, I have also received forwards from the department, when someone contacted the department heads with opportunities. So you could contact department heads personally.