Tag Cloud Widget
I'd like to see a tag cloud widget that you could add to the right hand column of your site. It might look like this, where the most commonly used tags appear in larger font. Clicking the words will bring you to posts with that tag. The manage tags link would be accessible to the admin and would allow them to manage, edit, and merge tags.
Seems like it should be a separate module. Will see how othe users will vote for it.
But you can do this module for your community right now with our Custom Script module.