How do I set up user's "Favorite Tags" and "Ignored Tags" tag subscriptions? This website shows user-specific "Favorite Tags" and "Ignored Tags" listing tags the user subscribed to. Based on these subscription lists, content is being sorted in "views". 


How do I let the users pick favorite tags?  
How do I create a "favorite tags" block like it is done on this site? 
How do I up Views to prioritize content assigned to subscribed tags?
Is it possible to use a Flags-like module to assign flags to taxonomy terms?
I would recommend using the Flag module to allow your users to pick "favorite tags".  It is still in beta for D7 however.  

Also, in the future you could look at the Flag Terms module to allow your users to flag taxonomy terms.  That module is still in dev.

You can use Views to create lists of "favorite tags", etc.