To paraphrase those pretentious financial commercials, "What can a show organizer learn from a British supermarket?"
This is where we're heading in the not too distant future. Faster than you can say, "Holy Whole Foods!".
If you've got a blog for your event (or even if you don't), this can be a mighty powerful incentive to get your audience vested in receiving your daily RSS feed.
Instead of using supermarket coupons, you'd be using show-only exhibitor specials, party/event invites and "insider tips" from your speakers that are not available to the general public.
Pretty nifty concept. Now who's going to try it first?