We use this to manage volunteers for our school's PTA and this extension is really perfect for it. It's got way more than we need for our uses, but it's highly customizable and it gets better and better with each updated version. The developers truly listen to feedback.
The support team is really great and for $75, it's truly a steal. We tried other free event registration extensions before going paid and they couldn't do a fraction of what DT Register can.