All Hail the Mighty Snark (with Respectful Regards to Killer Yap)!
I'm a children's author with a couple of books under my belt, and I was recently approached by the local education authority about doing some school visits and, if that works out, possibly conducting creative writing workshops for gifted and talented pupils in the area on a regular basis. This came about through the aegis of a friend who works for local government and had passed on my name and details.
I have just had a very positive meeting with the lady in charge of this kind of thing, and although I had made it clear that I was willing to visit schools for free, she did bring up the possibility of payment for doing the work. My question: if some money does materialise, should I have them send it to my agent so that she can remove her 15% commission, even though this work is not strictly related to my writing and has not so far required her involvement?
Double check with your agent. The answer is probably no but I don't know what's in your specific contract with her.
I don't take a commission on anything but what I sell, or cause to be sold. Thus, no commission on speaking engagements.