Poderosa is an open source tabbed based terminal emulator.
Unlike any other terminal emulator Poderosa allows you to work with split windows, so that you can easily run multiple sessions at once.
Another unique feature is that Poderosa can be used as a local shell for cygwin.
All typical terminal protocols are supported: telnet, SSH1/SSH2 and serial ports. Poderosa also provides a plug-in architecture allowing 3rd party developers to easily contribute new features and functionality.