Custom Wordpress Widget

I need a custom WordPress widget developed. WordPress has a function in which you can create a URL with tags and it will display all content with those tags. The URL structure is: http://yourblog.com/tag/music+apple More info here: [login to view URL] I need a widget that displays all existing tags and allows the users to select one or multiple tags and click "submit". Clicking submit will send the users to the URL with the above format, using all selected tags. Should be straight forward for the person who knows what they're doing. I don't need an options page at this point so it should be quick to implement. Bonus for anyone who can make the interface smooth, perhaps with AJAX. Requirements for this plugin: -Valid XHTML, CSS -Smooth, well marked-up code -No sneaky stuff -CSS styled interface when selecting tags