This plugin automatically converts keywords in a post title to tags, while ignoring a user-editable list of words.
This plugin automatically converts keywords in a post title to tags upon saving. It includes a user-editable list of words you want the plugin to ignore, which by default includes the more obviously-useless words like "I" or "wasn't." You can also reset the list back to defaults by deleting the current list.
Multi-blog adminstrators take note: this plugin is especially helpful if you're building a community-based site where tagging is important and your bloggers are not always diligent about tagging.