Question2answer TAG Search Adds a sidebar widget which allows searching questions via tag(s) Styling of the search box can be done via the admin interface. By default the box is using the styles from Snow Flat theme.
This is a beta code, using it at your own risk on a production environment. The code is using AJAX calls for retrieving tags and hence should not cause any performance penalty for page loads.
Plugin will be updated as and when required as it is being used on a very active Q2A site.