No you don't. There are a lot of revenue sharing sites where you can sign up for AdSense and display ads using your publisher id. See: http://code.google.com/apis/adsense/ For a list of revenue sharing sites, see: http://www.admoolah.com/blog/index.php/adsense-revenue-sharing-sites/ (which I must apologize for not having updated in about 6 months, yikes)
As someone previously pointed out, you can put it on a blog, but a blog is a Website. So yes, you need a Website. There's no way around that.