I really like the current domain management settings we have under personalized results -- still, I think it can be improved. For websites that contain multiple communities (such as Reddit) a blanket block on domain level is not very helpful. It would be great to be able to filter on more granular level, with a simple string / regex match we could filter out specific subreddits from search results directly.
It would be especially helpful on improving the search quality when using site search with @r etc.
I do think the implementation would be quite similar to how domain management is handled -- instead of just handling a TLD, it would be a short string / regex to match.