Are you looking for download link on http://fancybox.net/? Well it is not there anymore, because it’s author has removed it. And instead of that you should download/buy new fancybox from fancyapps package.
The problem is that new fancybox2 is not free as old one.
But do not worry. Here are fancybox 1.3.4 download links for you:
Feel free to download and use it. It is free software dual licensed under the MIT and GPL licences.
You can find more info about fancybox on: http://fancybox.net/