We actually don't have any dedicated budget for gaming at either my current or previous libraries, although the latter was made easier to bear by the presence of a long-standing (and not-poorly-funded) Gaming Society elsewhere in the school.
Unsurprisingly (and, to me, somewhat depressingly), Call of Duty: Black Ops II was by far the biggest seller, with Assassin's Creed III and Halo 4 likely the runners-up. Madden 13 and NBA 2K13 were also extremely well-represented among the gifting populace, as well as a smattering of Skyrim (aided, no doubt, by a temporary price drop and the recent release of the second DLC: Dragonborn). WWE 13 was another title that did well (a little too well in my store, as it sold out on both of the main consoles), while Just Dance 4 on both Wii and 360 was a heavy hitter.
Farcry 3 and the new Hitman game were somewhat underappreciated, I think, but that's likely because they came out so recently, and relatives have had Christmas lists since before said games were released. Mostly through intentional steering by employees, Borderlands 2 didn't do too poorly, although it seems there's still a general reticence to purchase any FPS game without the words "call" or "duty" in the title.
There were also a larger-than-expected group of the "show me all your games under $20 and maybe I'll pick something" crowd before the 25th, which is usually something I expect more on the 26th-31st of the month (when they also showed up). Most of them left with older CoD games or sports titles.
Incidentally, if you have a PS3 library, I definitely recommend the forthcoming Ni No Kuni (Wrath of the White Witch), which has both the animation/character designs and the story written by Studio Ghibli (who always does a nice job of blending childlike wonder with more mature themes into a package palatable for all ages). It was originally due for release today, but I believe they pushed it back to the 22nd - it's been out in Japan for quite some time now, but they're taking their time on the localization/translation (hopefully putting as much polish into it as Disney did for the various Miyazaki films they imported in recent years).