Tagging stuff in WordPress requires several steps and quite a lot of code.
Tagliatelle is a PHP-class for rapid development and easy tagging in WordPress plugins and themes. Make one single call to tag a post (or custom post type with a term). If the referenced term doesn’t already exist it is created automagicly. It is even possible to tag several terms to an object with one call.
Usage:
Load the plugin and use the class for easy tagging.
// Create a Tagliatelle object
$hottie = new Tagliatelle;
// Use it to tag the current post with the tag 'kers'
$hottie->write_tags($post->ID,'kers');
// If you want to, you can pass a comma separated list with tags.
$hottie->write_tags($post->ID,'tag1, tag2, tag3');
// It it of course possible to use / create tags in any taxonomy:
$hottie->write_tags($post->ID,'green, blue, red','supercolortaxonmy');
The current development version can be found at GitHub: https://github.com/bolstad/wp-tagliatelle