I bought my wife's birthday present on [broken link removed]. It's an irish site with free delivery and free gift wrapping in a nice box with ribbons and the works. She was very impressed that I didn't ask her what she wanted but got her something she liked and that doesn't happen very often!!
On this site, if you don't know what to buy, you can use their online tool which helps you pick something based on her age, the occasion, etc. They have the usual suspects of handbags and jewellery but they also have gift vouchers for beauty treatments and makeovers if your wife likes that kind of thing too.
Anyway check it out - it worked for me and I will definitely be getting her christmas pressie from them this year too.