In Sweden, H&M; has launched a project to collect funds and drive awareness around the HIV virus. Fashion against AIDS features a special t-shirt collection designed by a series of international music artists (Tokio Hotel and Cyndi Lauper among the others).
The website is pretty straightforward, you have the celebrities and the t-shirts you can immediately buy through the online store.
The attempt to generate a viral effect is supported by a (weird) branded avatar generator which, at least to me, looks a bit scary. Each avatar saved by a user is also automatically saved and posted in a dedicated photo album on Facebook. And this is probably the only aspect I really appreciate in this noble yet kind of flat project.
The agency is Great Works together with Isotop.