Searchable Tag Plugin

I’m looking for a plugin that will allow users to narrow search results by “tag.”

Ideally, the widget would be in the sidebar, and readers could click on any of the tags, and be taken to that series of posts. BUT – if they chose more than one tag, it would show posts with all the criteria they checked. Similar to the functionality that Amazon.com has on the left sidebar when you search for items.

Currently I am using the Faceted Search plugin, and it’s not working properly. But you can see the idea here at thebdn.com. Anyone know where I might be able to get this?