Therefore, this year, I shall share said ideas with you, so that I won't have all of these Brilliant Thoughts in vain. Or something.
For a future (or current!) Jane Austen fan:
Fiction: Depending on the age and interests of the giftee, pair up an Austen classic with a retelling or something along the lines of The Jane Austen Book Club, Cassandra's Sister, Stephanie Barron's Jane Austen mysteries (in which Jane is a sleuth!), or go for broke with a gift set.
The annotated Emma could be paired with Joan Aiken's Jane Fairfax or Mr. Knightley's Diary, by Amanda Grange. (There aren't a whole lot of Emma re-writes out there. See below for a couple of film adaptations, though!)
Sadly, Val McDermid's YA thriller based on Northanger Abbey won't be out until 2014, and while that's TOTALLY the one I'd go with (<--a statement based solely on my love for Wire in the Blood), you could also take a look at Marvel's comic book adaptation.
A Jane Austen (or Mr. Darcy!) t-shirt from Novel-T or something from Out of Print Clothing; a film adaptation—one of the usual suspects like Emma Thompson's S&S, the Firth/Ehle P&P, Clueless (Emma) or Lost in Austen, OR go with a lesser known one like Metropolitan (Mansfield Park in New York) or Aisha (Bollywood Emma!)—or something from this Etsy treasury.
As always, suggestions are very welcome in the comments!