Absolutely nothing! In my case both the giver and the receiver are incredibly cheap, and If I give myself a gift, then social protocol says receiving me must them give a gift to giving me, and that sets up an endless loop of giving/receiving and receiving/giving that led to me have 8 guitars I don't pay and 8 keyboards I rarely play (I could do with just the Kurzweil I have down here in my office area.) and a rack full of synth modules.
Plus I am also a grouch (or in this case, grinch) and I don't do holidays.
But to all of you who do get involved with this kind of thing, don't be cheap and buy yourself something nice!!
For you, Simon, I suggest a set of Sony MDR7506 phones. $90 at Walmart, or $130 from Sony if you want to feel like you are splurging!! I have 2 of these, one upstairs and one downstairs, and they are great.