It is a popular rule for the networking - never eat alone. And here is a mobile service for support:
NEA - lets you mark some cafe (restaurant etc.) where you are in right now as well as the time you are going to stay there. This mark (on practice - a mobile page) could be shared via email/twitter/facebook, so your friends are interested in will see your place and time they can join you.
Mobile site: http://nea.linkstore.ru
Short URL: http://bit.ly/e80a3G
You can use also the following QR-code:
P.S. there is a huge set of related services. For example: Places, City Chat, City Forum, Geo chat и food from Twitter.