Hummingbird Bakery make some of the best cupcakes in London (actually the world!) and their cakes are always gorgeous, as well as tasty. They are the kind of cakes that even people who don't like cupcakes (odd people) drool over. And if you, or someone you're buying a gift for is a fan there is a whole range of stationery available with their cakes on from Amazon (and from Waterstones (thanks Sarah)).
There are approx 10 items available in all but I've put a few of my faves on here for you - the full range is available here from Amazon or from the Waterstones link above. My favourite is the mini notebook and the notecards I think, but they're all just make your mouth water!
Also I noticed that a Hummingbird Cupcake Kit is available for pre-order (due out Feb 2010) which includes a cookbook and 100 cupcake cases - I'm assuming the cookbook is a edited down version of the original as it only includes 25 recipes.
And on a final Hummingbird note, don't forget their third store, in Wardour St, Soho, will be opening early December - perfect for a pre-Xmas shop treat :)