For my mum I'm setting her up a new HTPC down at the house, since at the moment it's just an XP box sitting there that I always have to fiddle with to let her watch anything. So I'll get a nice new HTPC with some good, easy to control software for her. I'm also getting her a new PC to use down at the house since she doesn't have anything there at the moment and lugging the laptop home from work is annoying (plus it's a slow, unwieldly machine).
Also a card, some of her favourite chocolates and a trip up to the mountains for some morning breakfast at one of the quaint little quiet towns with all those lovely open-air bakeries and restaurants that look out over the ranges.