Cinterion (Siemens) TC65 Java applet for tunneling RS-232 serial communication (MODBUS/RTU, GPS data etc) over GPRS/Internet. Works fine together with com0com SourceForge project.
Ponticulus (a virtual COM-port over TCP/IP redirector) allows synchronous connecting and disconnecting to a remote serial port (e.g. on an embedded device). It was initially based on com2tcp, part of the com0com project. (http://com0com.sourceforge.net/)
TimeFax is a Win32 program that allows you to send faxes from you computer to IP Network with any Windows Fax Application.
TimeFax is based on the t38modem (http://sourceforge.net/projects/t38modem) and com0com (http://com0com.sourceforge.net/).