I say just started, she's coming up the the end of her first semester. I've been looking around and I'm finding it hard to separate the crap from the good stuff. I'm not sure this is the place to ask this bit Christmas is coming soon and I'm a bit desperate.
EDIT: I stupidly forgot to include her specific area of focus. It's something to do with early Irish law texts... the Wisdom Texts? She's looking at female representation in them, I think. I'm going to visit her later so hopefully I'll be able to tease out a more specific summary.
EDIT 2: From a rushed Facebook text sent from a bus: "I'm looking at the discussion of women in the early medieval Irish wisdom texts, which are contemporary to and written by the same learned elite as the Brehon laws (medieval Irish law). It's interesting because they're all theoretical but imply significant contradictory interpretations of the role of women in the period." I'm sure it'll change as she comes to write her thesis and thinks about revising her work to suit a full-length PhD, but for now that should give a good sense of where her interests lie.
I actually disagree with other posters and think this is a great idea, because you're asking for help: all of the disappointing book gifts I've received have been when some just picks up the first pop-history they see with the word medieval in it. Proper academic books are expensive and so make a great gift for poor grad students, as long as you know what they need and what they already have.
I'm guessing that your gf hasn't specialised yet, which would obviously give more indications, but here's two titles I know any of my early Irish friends would love to own (just make sure you check her bookshelves to ensure she doesn't already own them!):
Thomas Charles-Edwards - Early Christian Ireland is the latest and best doorstopper overview of pre-viking Ireland and is always worth having.
Fergus Kelly - A Guide to Early Irish Law may sound specialised and dull, but it's actually one of the most wide-ranging and useful books written on the period, and a classic for a reason.
As far as what would make a good present instead of utilitarian reference? There are a couple of "holy grail" gifts among the medievalists in my department, if you'll pardon the (very medieval) expression. ;)
The first is something from the actual Middle Ages. A few people are lucky enough to have a manuscript folio. Coins are more common.
The second, and more in line with your request, would be lavish, color-plated book on manuscripts and illuminations. Something like Colour: The Art and Science of Illuminated Manuscripts or Beyond Words: Illuminated Manuscripts in Boston (in Boston library collections, that is). These provide illustrations and explanations of the folios, but also talk about the technical details of manuscript makings.
Gifts like these are popular because most of us own the actual books we want or have the necessary chapters scanned or some such. These are not typically the thing that a lot of historians think to buy, but they are really useful resources to have around.
Oh, and other other thing would be a published, original-language primary source that she's worked with a lot or might in the future (especially for her thesis). Depending on the publisher, these can be semi-affordable or completely cost-prohibitive for a regular purchase. Few things hit the nerd sweet spot like original-language primary sources!
Question that might help others - how much material from the same topic did she cover in her undergrad? Did she write a dissertation on early medieval Irish history?
But you'll have to get it couriered last post was 4 days ago.