Horacio's Message
Horacio will live 365 days. He is a sobrenatural human being, who has a message for the world.

Solution

On january 1st - 2011, a man finds a basket with a newborn baby. Strange messages are slid under his door. The man starts writing a blog, where asks commentors for advice. The baby seems to have supernatural powers (levitation, speak in tongues, genius skills...) and an important message for humanity. One important Horacio characteristic, is that every 4 days, he is one year old. So in January he is a baby, and in December, he is an old man.

Blog commentarists could find whether Horacio has this message or not, whether Horacio is an angel or maybe a demon, maybe his existence deals with alien intelligence, maybe it's only a sort of twilight zone history

You can see a test for this interactive blognovel in this blog:
http://365novela.blogspot.com/ (It's from year 2006, and basically is the same history. It started January 1-2006 and ended December 31-2006, with the character of Horacio living 365 days) Hope you can translate it with google translator   ;)