My social life in the internet is fairly highly compartmentalised, largely due to enjoying several different hobbies that have only marginal overlap.
Thus most bass players who frequent basschat.co.uk aren't particularly geeky when it comes to computers, and tend to be firmly left-wing liberal atheists.
The guys I know on Harmonycentral.com are mostly US citizens, and therefore right wing (even the Democrats, relatively speaking).
On Worshiptherock.com they are further right, mostly, than harmony central, and also evangelical Christians with just a few exceptions.
My friends on the second fastest declining secret forum (boring URL though) are mountain bikers from a variety of disciplines (including a real rocket scientist, laser technician, bike shop owner and a lot of less exciting jobs) but conversations are often about which tour rider will confess, who has died recently and about squirrels.
There's libertree, which is full of privacy and activism advocates, all keen to put the world to rights and display the politicians and bankers for the criminals they are.
Then there's google+, which is gradually filling up, but is still pretty exclusive to a geeky few.
Finally there's Facebook. It's like a small river in which everyone has come to swim, and in so doing, caused the water to trickle muddily along, making everyone who lives there seem like a child playing in a puddle.
There are just a few who cross the spaces between, but it's VERY strange moving from place to place, wondering how the discussions would go if people from one group began to interact with people from the other.