I've given a few talks over the years and these are the results.
My first talk at FE Suffolk was about colour theory. Most people just looked at me blankly but it was fun. I've done a couple more since then, one about Unity and one about three.js, both of which are written up on the blog.
I've also spoken at Dorkbot which was about how I hacked up a cheap webcam and fitted it to our telescope.