A gadget would be a bit dodgy unless you know that s/he wants something specific. No point giving something that'll sit in the cabinet un- or little-used.
Cookbooks that one would covet are Wendy Hutton's new one (forget the exact title) and anything by Christopher/Terry Tan (son-and-dad), as well as the 3-book range of "Cooking with Asian...(roots, leaves and something else)" by Devagi Shanmugam and Chris.
A classic book to give - but if the giftee is a diehard cook s/he may already have it - is Elizabeth David's An Omelette And A Glass Of Wine. There are other books about cooking which are great reading too - like memoirs/cookbooks - a peek into the Kino cookbook section will help.