Most projects take place Friday, October 24 and Saturday, October 25, though a few are scheduled before the main weekend. You can see the full list of possibilities here -- just choose any marked "(GDOS)".
Participants receive a t-shirt, and when you wear that shirt to one of three Gwinnett Stevie B's restaurants on the 24th or 25th, you get a free pizza buffet.
You can sign up for the event as an individual, group, or business. See details at GwinnettGreatDaysofService.org.