Rails tagging solution
52745
Best Rails Tagging Plugin/Gem
128981
Searching for question having strictly a certain set of tag
92655
Automatically show which tags were edited in revision history
23298
Searching for questions that have ONLY a given tag (i.e. add a range operator for tags)
106532
Tag hierarchy to browse through tags
72253
Excluding tags from search results
87240
Search by multiple tags
56515
Question tag score and suggesting tag synonyms?
122614
RSS feed of your favorite tags
67764
Rails: What's a good way to validate links (URLs)?
35575
Automatic tag suggestions
38574
How do I combine/exclude multiple tags from a search?
49379
How to subscribe to tags?
90883
Tags on badge question list
158369
How to Disable new terms (free tagging) with Taxonomies?
107498
Answering tag questions
54586
How should ambiguous tags be dealt with?