I play competitive pinball and have made many good friends through the hobby!
Also, its great to have a focus when traveling for work or pleasure. Always check a Pinball locator map before I hit a city. Good way to find cool bars in strange places!
Similar to nay bar game, pool, bowling, darts, etc. Give me an excuse to go for a pint and have some friendly competition.
Also, since Music is a hobby as well, I have made a lot of good friends while looking for work and collaborating with other musicians.
Funny that growing up, the bands i was in during high school, it seemed that we were all friends before being in a band together, now its the other way around!