I've been using the 'How do I add a Top Posts widget to my blog?' trick from the bottom of this page http://wordpress.org/extend/plugins/stats/faq/
I finally figured out why it stopped working for me (the way I use it) a few days ago - the post_id variable in the array stopped being set.
For the home page it is being set to 0, and for all other pages I checked it is just empty. var_dump($top_posts) to see what I mean.
Is this coming back - I really need it.