Is it appropriate to put talks that are not related to research, but given at an academic institution, on a CV? I've given a talk at an academic institution that is not related at all to my math research.

Is it appropriate to put talks that are not related to research, but given at an academic institution, on a CV?

The sort of talks I am thinking about are ones about personal experiences, or something related to an interest that is not related to one's primary area of research.
Absolutely! 

There are a number of talks that I've given that aren't related to my own research that I consider to be some of my most influential talks. In particular, I think talks about academia in general, or about the publication system, or recently, a talk about open access and open science. Taking the time to speak to younger academics about things about which you are passionate (like for me, preprint servers like arxiv.org and biorxiv.org) is very important.

I have also had the opportunity to give a few talks not even at academic institutions that I consider to be worthy of 'academic credit'. Specifically, I spoke at TEDMED a few years ago, talking about the medical education system, which you can see here:

http://www.tedmed.com/talks/show?id=7331

and also at an event called Pint of Science (pintofscience - podcasts from me and many others here: https://pintofscience.us/podcasts/ ).

I've been asked more about these talks at interviews than any others! I think especially in a world where all academics applying for jobs/tenure have excellent CVs, having some 'non-academic' stuff on there can help you stand apart - and show another dimension of you that folks could be interested in.