Any good tips on how to run a good networking event

I recently started a Meetup.com group for the Energy Services Sector in Calgary and we are going to have our first networking event this week.

The event is in a pub where people can meet, introduce themselves and network.

I was hoping that people might have some great ideas for making a networking event a success? -salestipaday

Have you had any success with netowrking groups from meetup? -salesfist