uses tag-min-length and tag-max-length constants
supports AdminTags
maps tag-urls via separate url-mapper, includes permissions (admin_only or dont_care_logged_in)
all tags are converted to lower-case
compares new tags to already existing ones if not inserted by admin
all tags are treated equally (no levels or tagging-classes)
deletion of tags allowed
has pretty complex database-layer which creates sql-statements based on changes in php-objects. (this part might be useful, at least it could be valuable as 'code-snippet')