Cameos of Erfworld Characters, and guest strips in other comics.
Some figurines from what is apparently an Erfworld tabletop game appeared in Weregeek's 100th page. These include a green dwagon and a pink dwagon, two gwiffons, some marbits and Woodsy Elves, and what might be Bogroll and Parson.
 Finders Keepers
In Finders Keepers, a splash panel after entering the Wyrd Bazaar includes a monster merchant, who is reluctantly admitting that he doesn't carry dwagons.