Orico USB 3.0 and eSATA External SATA HDD Dock
Every enthusiast knows the pain of having a spare hard drive around that you need to get data off of or make sure is blank before giving it to a buddy. This Orico external HDD dock allows you to connect any 3.5-in hard drive to your PC through USB 3.0 or eSATA for impressive speed and flexibility.
ASUS PQ321Q 32-in 4K 3840×2160 Monitor
I tried to keep this off the list, I really did. I don't want anyone to go broke over this kind of thing, but using the ASUS PQ321Q 4K monitor in person is really a sight to behold and can't be expressed in a dramatic enough fashion over text, audio or streaming video. With support for 4K resolutions of 3840×2160, the ASUS PQ321Q results in 4x the resolution of a 1920×1080 monitor and you'll quickly find a lot of use cases for this much real estate. For gamers you'll see detail that you haven't seen before but you'll likely need some pretty high end hardware to power it all. Developers will find the added pixels a savior for content creation. There are a lot of reasons to love the PQ321Q but the price isn't one of them.
Seiki Digital SE39UY04 39-in 4K 3480×2160 TV/Monitor
This is certainly (at least one) step down from the ASUS PQ321Q. Still, it is an order of magnitude cheaper. Most notably, you are limited to a single HDMI input and thus 30 Hz; gaming will not be too pleasant. You are also limited to all of the other quirks of a TV. But, if you want a big panel with a lot of pixels, this is about the only semi-impulse-affordable option.
I hope you did not go cheap on your GPU, though.
LG Electronics 14x Internal Quad Layer Blu-ray Writer
If you are concerned with long term data storage, then you could do worse that picking a quad-layer Blu-ray burner/writer. With the ability to store up to 100GB on a single disc, it's still not up to the level of storing things on an external hard drive but it is definitely convenient.
LG Electronics 14X USB 3.0 Quad Layer Blu-ray Writer
Another BluRay writer because all good PC accessory recommendations this year comes in pairs? Maybe your gift recipient cannot install an internal Blu-ray drive. Maybe they have multiple machines and would like to share one drive between them?
Maybe they are… a Mac user. Give them a gift bag of hurt this holiday! They will probably have some issues on the software side of things but owners testify that it will work with Mac OSX 10.6.8 (Snow Leopard) and later.
The price is a bit steep compared to other offerings (you can find USB 2.0 BluRay Burners for the mid $80's) but I expect that USB 3.0 will be worth it. On the technical side of things, it will support just about anything I can think of including multi-layer BDXL discs up to (LG claims) 128GB in capacity.
The price could easily be justifiable, especially if it is just one optical drive to swap between every machine.