Q:

Tag redirect to appropriate site? 

Do you think it would be possible to create a tag search and redirect for all StackExchange sites? 
For example, if you are a new user and don't know what site to ask a question you could search related tags to your question and those would suggest the best place to ask your question.  This might help new users find the best location for questions and prevent some unrelated questions.  Do you think this should be added? 
Details of how it could work:

Users type a question on any stack exchange site. 
coding analyzes the words from the question for keywords and generates a list of suggested tags (the tags would be composed of a dictionary of tags for all stackexchange sites which themselves would be tagged by which site they are used on)
From the suggested tags, the code would suggest a recommended site to ask the question.  If the current site is not the recommended match it would have an on page error show up before submitting. ( The question could still be submitted but would give the suggestion of another place to post the question.) 

A:

I doubt this was the intended use for filtered questions, but you can get a list of sites that have a certain tag:

This is the easiest way to find which sites have which tags.