Possible phase 2:
DeleteDo something with questions with score <= 0, no accepted answer and no answers with score >= 0 after three months
If I did my query right, this is about 44,000 questions, which seems like too high to me (as in, not an accurate count. Are things really that bad?). Deleting this many would definitely have to be considered very carefully.
http://odata.stackexchange.com/stackoverflow/s/609/qs-with-no-as-0-after-three-months
This query will let you browse the affected questions that actually have answers so you can judge what sort of treatment they need: http://odata.stackexchange.com/stackoverflow/s/610/view-deadweight-phase-2-questions
As an alternative to outright deletion, theseThese questions could simply be removed from the Unanswered tab into a new status called "Expired". Wouldn't need it's own tab, questions could just be accessable by searching. Though after looking through some of them, I'm not convinced they'd be a big loss.