Make a point of talking to someone you don't know. It's really easy to keep in your circle of friends - it's comfortable and fun. But a lot of new interesting relationships will come from reaching out. I find that most other people at tech conferences tend to be shy as well, so reaching out isn't really difficult - people respond well as if they were just waiting for someone to include them.
Go to a talk/presentation that might sound like it's not at all up your alley. You might like it after all.
Stick around after a talk and chat with the talk attendees - a lot of interesting and meaningful conversations happen right after a talk, when everyone is excited about the topic but there is no pressure to raise your hand in a big room full of people.