We found a dev who has started work on it, please PM me if you want to contribute to the project and get access to the resource when its done.
I've worked with another forum that does this in an incredibly manual way, but it's a HUGE draw for their forums.
Working with local companies to make sure everyone benefits. (They can send an email to their clients promoting it, you can share your clients with them, you get exposure, they get exposure, all in all, very cheap)
Our giveaway was sort of similar, but a lot easier to enter - everyone got a weekly entry (random number - by clicking enter via their profile) but there would be bonus entries a few times a week too (with conditions, e.g., post on the forum today) it kept people coming back and the brand in mind throughout the whole year (we gave one away per month). It was a fun project - I coded it in Rails and put it in a sub domain.