Part of what I do is carry the flag for exotic gardening and, for some years now, have been giving illustrated talks to horticultural groups, clubs, U3A, colleges, at seminars and even once to one of the RHS committees.
I have a few set subjects, for example 'Introduction to Exotic Gardening' or 'Gardening with Succulents' but will happily tailor the talk to the requirements of the audience. All I need is a power supply, a roof and an audience. I recently upgraded to using a digital projector and 2.2m screen
I also give illustrated talks on my plant hunting adventures to Mexico with a focus on any aspect of any or all of the trips - plant-lite or a detailed agave study!
Mexico: above left - pre-Columbian ruins at El Tajin near Papantla, right Agave scaposa, Oaxaca.
Above: gardening with succulents