Molson-Coors Canada recently made their ads interactive with "Brew Your Own Beer Ad"
It's a contest based on this current Rickard's "Pint of Delicious" TV campaign:
In the online version, you get to script the comments of the three barflies (or be like a real Copywriter and "borrow" an idea...)
The guys do your bidding, with weirdly animated faces and electronic voices. You can make them say anything you want, but profanity gets a "look" and some snark from the barkeep.
(Hey, pal! It was in the name of advertising science!)
The content is also sharable, but in an effort to avoid an epic viral brand hijack like GM had with its Chevy Tahoe make-your-own ad application, your link is only sent to a friend after some sort of comment moderation. (Even some clean, but inappropriate versions I attempted failed to get through.)
This lack of shareability is generally a detriment to a viral campaign, but given the negative brand associations possible to inflict on the alcoholic beverages category, it's probably wise.
Plus, it's only a matter of time until someone finds a way to share their sick ideas.