I don't know if you've heard about this yet, but it's catching on.
Twitter
One of my mentors joined and started doing Tweets every so often. It's actually a great networking tool also... finding people you'd like to network with and seeing who they are networking with and etc.
Yes, kinda like LinkedIn, big deal right?
Well the whole tweet/messaging thing makes it a bigger deal because you can follow what these people are doing day-to-day. (Slightly voyeuristic, I know)
As a marketing tool it could become quite remarkable. For a restaurant It would be a matter of creating a profile and getting people to "follow" you. From there it's fun and games... and relationships.
Tags: 2, marketing, restaurants, twitter, web