These aren't two of ours - want to get that clear straight up, so that nobody thinks I'm claiming them. Not too proud to admit that there are other people out there producing visionary grabbable goodness :)
The CLOVERFIELD widget is nice and simple, and, crucially, offers a really juicy five minute excerpt from the movie, along with a simple, clearly communicated incentive for people to spread the word.
It's just a shame for the rest of us that the chance to host an advance screening of the movie in your hometown is only available to "legal residents of the 50 United States, the District of Columbia and Canada (excluding the province of Quebec)". Damn those guys in Domestic have it easy.