Volunteering as an IT support guy is still terrible ROI for most people here.

Volunteer work in general is mostly about spending some of your time to get a good feeling for yourself, and advertising the charities in question. Basically everyone who haves a profession of any kind gets the best ROI in charity for their time by working, and donating the money earned doing so. This is abstract and feels less like helping people, but if your purpose really is to help and not purchasing happiness for yourself, it's what you should do.