I know a lot of people do run regionally themed tanks, but I don't recall everyone off hand. I know
@Nman does a coldwater, UK rock pools tank;
@TangerineSpeedo runs some temperate tanks - I don't recall at the moment if they're region specific though;
@Reefkeepers Archive is trying for an Australia specific one; lots of people aim for Caribbean-themed tanks, and a few others aim for different biotopes like Atlantic-themed, Great Barrier Reef, Okinawa/the East China Sea (I know
@Zionas was thinking of doing this biotope, but I don't know if he ended up doing it or not), Puget Sound (some really cool stuff like Grunt Sculpins from here), Long Island Sound, Chesapeake Bay (an oyster reef), Hawaii, etc.
I know a lot more people keep cold/temperate tanks, but I've found it hard to find pics of the tanks.
Personally, I really like the Puget Sound stuff, and I'd love to see some Japanese biotope tanks, as Japan has a lot of cool sea critters.
Some examples:
https://www.reef2reef.com/threads/carribean-biotope-style-im-20.984743/https://www.reef2reef.com/threads/puget-sound-biotope.806998/https://www.reef2reef.com/threads/chesapeake-bay-oyster-reef-biotope-tank.303105/vlangel beat me to the oyster reef one.