007
007 is earned by reaching a score of 7 on an answer of yours where both the answer and the question have 0 comments.
Why not just call it "7"?
Amazing Grace
Ask a question tagged [bug] with a +10 score, that has an answer with a +10 score. Confirmed as such, status and accepted answer status don't matter.
Not the admiral's most important work, but her most famous.
Archimedes
Archimedes is earned by correctly guessing the trigger for a secret hat. It is this year's equivalent to previous years' Eureka.
Solve these riddles and it's yours. (Sound familiar?)
Cleanup Crew
Cleanup Crew is earned by deleting 10 of your own comments on posts that fulfill certain criteria: the post was edited after the comment was posted, the edit was made by the owner of the post, and the owner of the post is not you.
It's not garbage until it's served its purpose.
Edward Edwards
To earn this hat, you must win a bounty even though a competing answer had already met the criteria for the bounty to be automatically awarded.
Tahiti, 1791.
Flip Flop
It exists in two varieties, blue and white. You get this hat for voting or posting on December 22nd (the usual time zones rules apply here - starts about 14 hours before it's December 22 in UTC).
It's actually just one dress hat, which will become more obvious in better lighting.
Flying Tiger
Answer a question with a -3 score that later goes to +3, and your answer is +5. This is very similar to last year's Red Baron.
It's important to know your history... in more ways than one.
Hairboat's Revenge
Hairboat's Revenge is earned by commenting on one of Jon Ericson's posts, or by replying to one of his comments. It cannot be earned by doing this on a per-site meta, only on main sites and Meta.SE. This hat is in retaliation to one of last year's hats, which was the same except that it was targeted at abby hairboat.
Turnabout is fair play.
It’s Always 5 O’Clock Somewhere
It’s Always 5 O’Clock Somewhere is earned by posting a question when it is 17:01 on Friday somewhere in the world. The question has to be upvoted to count.
Rejected hat name: "What Are You Still Doing Here?"
It's Over 9000
Ask questions that accumulate 9000 views together. Can be earned in one question, or multiple. Potential limits not identified.
One not familiar with the meme might argue that a better name would be "They're Over 9000!"
Odinson
Closing/Flagging a post as a duplicate before it is dupehammered by a gold-badged user, or be said gold-badged user.
What if Mjolnir were made of gold?
Onion Knight
TOR - The Onion Router. Second word. Concept of anonymity: post a question that received at least three anonymous feedback pseudo-upvotes from visitors who did not have full voting privileges on the site.
What's a better hint, the first word, or the second?
Sun Wukong
Sun Wukong is earned by writing a post on a meta site that receives at least 5 upvotes and at least 5 downvotes.
Mostly a good guy, but not always.
>!
spoiler formatting so as not to ruin it for the rare folks who want to figure it out on their own