Selectize is a jQuery-based custom
<select> UI control. It's useful for tagging, contact lists, country selectors, and so on. It clocks in at around ~7kb (gzipped). The goal is to provide a solid & usable user-experience with a clean and powerful API.
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.
Tokeninput is a jQuery plugin which allows your users to select multiple items from a predefined list, using autocompletion as they type to find each item. You may have seen a similar type of text entry when filling in the recipients field sending messages on facebook.
This is a highly configurable photo tagging plugin. It’s primely for tagging people on photos but it can also be used to create notes, but you will need to adapt the form part a little bit. The code is really clean and easy to understand, it follows the jquery plugin recommendations.
Here is awesome 3D tag cloud that is available as a jQuery plugin. Tags are sized according to weight. Touch / drag within the black box to rotate the tags. Mouse wheel zooms. It also works on touch devices.
Filtrify is an advanced tag filtering plugin that you can search tags within tags and filter items by multiple tags from different categories and get a live feedback on the number of items containing related tags.
jQCloud is a jQuery plugin that builds neat and pure HTML + CSS word clouds and tag clouds that are actually shaped like a cloud.
jTag is a free jQuery plugin that allows you to give a image tagging system on your site. You can add more information to your images and offer a more interactive experience to users.
TextExt is an autocomplete and tag input plugin for jQuery which allows you easily turn a standard HTML text input into a wide range of modern, tailored to your needs input field without bloating your source code and slowing down your site with the code that you aren’t using.