Yogurtsburgh is a frozen yogurt shop located inside the Greendale Mall. When Abed looks into the shared history of the Study Group, the location was discovered to have played an large part in it's eventual formation. It's first appearance was in the Season Four episode "Heroic Origins".
In the Season Two episode Advanced Dungeons & Dragons, the map showing Fat Neil's journey from his old "Evil High School" to Greendale Community College shows a "Good Frozen Yogurt" place close to Greendale. This may or may not be Yogurtsburgh.