I advise companies of various kinds from time to time. Sometimes formally as-in contracted and receive compensation (stock etc) for my contributions, as part of a higher-ed mentoring program. Other times sorta in-formally because i believe in what they doing, they are nice folks/friends and i just want to help.
For the record, here’s a list (with related comments as available):
Sons of Vancouver
Rural Caprine Farm
Dr. Erikson, TCM