Record Volunteer Hours and Service Performed

I help manage a large group of volunteers who perform service work throughout the year. At the end of the year, we ask them to provide, by category, the service hours they performed. Response is often inaccurate and only represents a sub-set of those who actually performed service.

I’d like to find a WP plug-in which will allow individuals to report service work throughout the year as they complete each project, possibly as often as each couple of weeks. I considering the Participants Database plug-in, but it seems more complex than I need.

Is there something else that would meet my needs more efficiently?