Tokenize2 is a jQuery plugin that allows you to select multiple items from a predefined list or ajax, using autocomplete as they type to find each item.
Tag-it is a jQuery UI plugin to handle multi-tag fields as well as tag suggestions/autocomplete.
Taggle.js allows you to create tag fields within your forms, to allow for easy and optionally restricted, input from your users.
inputTags.js is a simple jQuery plugin allowing to add, edit or remove tags in a tags list.
Insignia is a customizable tag input that is progressively enhanced, fast, easy to use, and reliable.
Tagator is a jQuery-based replacement for input boxes, making them tagging boxes. It supports searching, and affects the original input box directly, which is used as a comma serparated data container.
Tag Editor is a powerful and lightweight tag editor plugin for jQuery.
taggingJS is a jQuery plugin to create an high customizable front-end tag system. It is less than 2.5 kb and support major browsers in the world!
jQuery.masterblaster is a nice and tidy tag manager.
Inputosaurus Text is a jQuery plugin that allows for multiple delimited values, parse hooks, autocomplete, keyboard shortcuts etc.
The jQuery Tagit plugin transforms an html unordered list into a unique tagging plugin. Why unique? Because jQuery Tagit uses jQuery Ui's auto-complete plugin to supply suggestions to users as they type.