I like seeing photos of people's handiwork in the Aussie mancaves Facebook page. Here's a good one I saw recently of an old shed turned into a backyard pub.
Here's my dream man cave - this guy in the states set up his own retro video game arcade in a barn. It has over 50 machines.
I've heard that @NickM has a shared inner-city workshop. Care to share some photos that might inspire other members of the community, Nick?
He has pinballs too @Jackson.
Here's a couple more pix. A Flash Gordon pinball would be pretty rad.
There was an awesome bar and carport conversion at this house in Heidleberg Heights, but I think the realestate agent thought it was tacky and didn't include it on the images, you can just see it poking out of one of the images: