There are a couple of ways to view your existing connections.

1) To view a complete list of exiting connections, simply go to the Connections menu and Connected tab.  This complete list of your connections can be sorted by date or last name, and can also be searched.

2) To view connections that are within your proximity (i.e. also at the airport or convention center), simply go to the Nearby menu and List tab.  This page offers several filtering options, including the ability to see just your existing connections or just your existing connections in the same network.  Existing connections are indicated by the link icon.