Wow, it's like coal that eats through the stalking.
I pulled a new pair of Nikes (convenient since my last pair of shoes came to me some number of years ago, used, from an immigrant truck driver), $200 in "entertainment superstore" gift cards, Silence of the Lambs, an appropriately bookish-looking statuette, a decent amount of shirts/socks/boxers, and the usual cheap stocking-stuffer curios. Oh, and, jointly with my girlfriend, a copy of the mega-deluxe fancypants edition of Spore.
That's more than I've received in all the years since I left home, combined. Getting in tight with your girlfriend's family can be a little off-putting for the habitual bachelor, but it's definitely got its perks.