I came across Datanyze which crawls websites and puts them in lists according to what powers them. It turns out they have a job board software list. (view list)
This list is not quite accurate however. I have never heard of Job Gear and couldn’t seem to find anything about them online. But this list is interesting to look at nonetheless. No one really uses JobberBase anymore but they appear to have a lot of legacy sites running on it that are still live. Platforms like JobThread are also not active any longer though they still have live sites.