This is a pretty easy one, since RPGs naturally fit in a constellation of various hobbies. Wargaming is the one that gave it birth and miniature painting goes hand-in-hand with it. Computer gaming was born out of tabletop RPGs, and as such, computer programming is another hobby that follows this path. Consuming media is necessary to develop new stories, so goes well with RPGs. Finally, I’d say that artistic creation like writing, drawing or creating other works of art that complement or are part of the RPGs definitely fit the bill.