I've been seeing lots of questions (well a few) marked as "off-topic" for DSP.SE, with just the "This question does not appear to be about signal processing within the scope defined in the help center." option chosen.
Several of them actually belong on another StackExchange site (usually Math.SE or EE.SE), but I've never seen someone suggest that.
If you suggest that, it makes it easier for me and the other mods to migrate the question to the appropriate site.
When I click on that option, I get the ability to search for the right Stack Exchange site: