*UPDATE*: This plugin is now being hosted on the WordPress.org repository! Please visit the WordPress page to download the plugin here.
Alternatively if you’re interested in the code, you can find the SVN repository here.
Currently working on an open source WordPress plugin that allows for front-end tagging of posts. It uses jQuery UI autocomplete to search the WP DB and return the closest matching tag based on the search term. If no tag was found, you can add a new tag by simply hitting the enter key.
Here is a screenshot of the widget: