Whenever people have asked me to speak at any of their events, I have never asked for any money. Sometimes I have received a modest honorarium, but I never made that a condition for speaking. I have been speaking at private events (e.g. the 60th birthday of a professor in Munich), conferences of professional organizations (e.g. the AGP 'Open Source' conference in Hamburg) and of course, in the vast majority of cases at scientific conferences, universities or other research institutions. None of these are for-profit organizations and the overwhelming majority is even tax-payer funded. Thus, I think asking for an honorarium would unethical: the taxpayer is already paying for my research, why should they pay again? The argument is similar to the Open Access argument: publicly funded research should be publicly accessible. Hence, no honorariums. Travel costs are usually paid, of course, but I never ask for anything beyond my own costs of attending the event.

Yesterday, for the first time, I have been asked to speak at an event of one of the largest conglomerates in Europe. In this case, I'm not sure what to do. In principle, I would speak for free as well. However, two reasons make me hesitate. For one, would be speaking for free just entice more people to ask me to speak, keeping me from doing research? And second, shouldn't corporations pay for the rersearch they then use to make a profit? An honorarium would not only make corporations pay at least a little bit for the research, it would also mean that only those with funds to pay the honorarium would invite me to speak at their events (is that really the kind of organization I want to speak for?).

If I ask for an honorarium, however, how much should I ask for? Clearly, the honorarium would either go to charity or pay for scientific equipment in the lab. If the company pays the honorarium to me (and I donate or buy equipment), there are limits to the amount of money I'm allowed to receive. If the company donates to the lab or the charity directly, there are no limits, AFAIK, or at least other limits (need to ask what the limits are for universities, if there are any. Not that I think I'd be even close, just to get an idea).

So, honorarium or not, if yes, how much and for charity or research?