I spend a LOT of time with tunnels open to multiple machines, connecting directly to PostgreSQL, RabbitMQ and many other services all via SSH.
I have written several helper functions and this is the final version that I created in a small competition with @codeinthehole.
Simply add the contents to ~/.bashrc
Usage is pretty simply, just called portforward from the command line, pressing <TAB> as you type in a server name from your ~/.ssh/config file and the same with the port.
portforward syslog.tv 15672