My problem / use case:
I'd like to know when someone creates a question with the a certain tag on the StackExchange network, so that I can (1) answer the question, or, if necessary, (2) advocate that the question be migrated to a more appropriate site/closed as a duplicate of a question on another site. For instance, if I monitored the electronics tag, I could answer this question on Bicycles.SE. I have no idea if, say, Cooking.SE will tomorrow have a question by someone with a burned-out food processor.
The filters/tag sets and associated feeds are a great tool to solve this problem. However, many of the related tags that I'd like to filter are heavily represented on Electronics Design, which I monitor differently. Therefore, I need to exclude Electronics Design from the filter.
Why the current site doesn't solve my problem:
Currently, if I select a set of sites (not including Electronics Design) on the filters page, and then type in a tag name, any sites which don't currently use that flag are eliminated from the selection. This is a neat feature for some use cases, but it makes it impossible to exclude a single site (or small group of sites) from a filter.
Proposed new feature:
I'd prefer to have a third radio button in the list:
I'd like to include...
( ) All Questions
(o) Just questions tagged [______]
on....
( ) All sites
(o) All sites except: [______] (+ checkboxes below)
( ) Just these sites: [______] (+ checkboxes below)
over simply eliminating the feature which limits "Just these sites" to sites which currently have the tag, because then I could catch new questions on sites which haven't been created yet.
Can we change the filters page so that a site (or set of sites) can be excluded from the filter?
Excel
but not if they are from the Portuguese or Japanese site, because I don't speak these languages.