As we move into mid-December, it's not a bad time to begin to get ready to move into 2012. In this vein, I'd like to ask the community to pitch in and help out with some spring winter cleaning.
To that end, here's a list of things that we could do:
Closing
There are some old questions that should now be closed, either because they were missed in the early days of the site or are now off topic due to changing site policy. If you have 3k+ rep, you can vote to close them; otherwise, flag for moderator attention.
Deletion of closed questions
Questions closed off-topic, not a real question, too localized, or general reference can mostly be deleted. If you have 10k rep, you can vote to delete these; if you don't, you can flag for moderator attention. If a question is not constructive, please make your best judgement call, looking especially at the answers. If the content is valuable, we might want to keep it (see Locking); otherwise, out it goes.
Please check that these questions should still be closed; do not just blindly vote to delete or flag, as questions may have been improved.
Duplicates and Mergers
If a question is closed as an exact duplicate, it's probably fine just to leave it alone. However, if the questions are phrased so similarly that you could put the answers of one under another without any editing, please flag for question merging.
Locking
Some questions were asked on the site a long time ago that are no longer a good fit for our site. Most of these questions should just be closed and deleted. In cases of historical significance, however, the post can be locked, thus preventing activity while allowing preservation. Very few questions deserve this—in fact, we've only ever locked three questions with this banner, but if you see any that should have this protection, please flag it.