Those links at the bottom of posts that say “Tags: foo, bar, baz” should now be working.
Back when I started this weblog, WordPress didn’t have keyword support, so I installed a plugin to implement them. Then at some point keywords became a core feature of WP. I think that having tags in the core and keywords in the plugin broke things.
So I finally consed up a quick and dirty kludge to transfer all of the old tags to new-style keywords, deactivated the plugin, and things started working again. Yay!