Have a 'tags' page, show diffstats via churn
The 'tags' tab at the top of the page is not clickable, but when you hover over it all tags are shown in a menu. Click on them to view the source as of that tag.
How about also making 'Tags' a link to a tags page? It would show all tags, including 'tip', in a list down the page, and for each one would be output similar the the built-in 'churn' extension. Except that instead of ascii text, use google charts (or whatever).
The idea is it would give some clue as to the amount of work, and who did it, for each release. And with the tip tag included, it would give a strong hint whether you should use a released tarball or whether a lot of work has been done that has not yet been released.
Another visualization might be to at the top of the page, show all tags on a horizontal graph spaced according to time, with the height showing amount of churn between each tag.