It all started with clearly technological SO, SF and SU. Followed by bunch of more or less IT related SE sites. But recently more and more SE sites with no relation to technology at all are created. I feel mixing them with still mostly technological SE creates lot of noise. And hardcore programming sites being the most popular, I feel it creates even more noise and confusion for the newcomers in the non-technological sites. I mean, do you really expect someone who comes to let's say Fitness & Nutrition SE to be able to even understand what hot question "difference between factory pattern and abstract factory?" is about?
Ideally you could have some clustering algorithm, which would show to the users the sites that are interesting to him based on sites and tags he's active in. But for quick and dirty fix, separating technology from non-technology could be a great improvement.
EDIT: I'm not exactly sure how it should look in detail, thus this question is tagged discussion not feature-request. I imagine that if you'd log in into let's say StackOverflow, you'd see technological part, while if you'd log into let's say Cooking, you'd see the non-tech part. "Tech" and "non-tech" are descriptive, actual names to be used is something that would need to be discussed. Also the way of cross-linking between them.
EDIT2: I know that kind of separation isn't perfect. But if you remember for example Usenet, it has Big 8, where computer related (comp.*) are clearly separated from recreation and entertainment (rec.*).