Vampires, which you may already know as the RPG where members bite each other to receive points (and duel) was already popular with over 3 million installs in Facebook.
Sony pictures, the parent company of the very scary 30 Days Night vampire horror film rebranded the existing application, and launched a sweepstakes contest to generate registrations and glean intelligence. The grand prizes? 4 wheel ATVs and $1500. Specifically, they placed banner ads on the rebranded vampire applications which promoted the movie (one could assume that those who opt-in for the vampires application would also like a vampire movie) promoting the sweekstakes.
The measurable results
The campaign was only live for 3 weeks, and there were 59,100 sweepstakes entries. (success was deemed at 10k, this clearly moved beyond that) The visits (I don’t know if they were unique or repeated) were 11,642,051 for the bite page, and 17,652,567 for the stats page (I believe these are part of the interactive experience of the game. Sony was happy, it exceeded expectations, and users of the application weren’t over branded.