iMobimac Modem
The Research In Motion BlackBerry is famous for its connectivity. iMobimac Modem runs on a BlackBerry and the Mac to which it is connected, and lets Mac applications access the Internet using the BlackBerry's connection.
The BlackBerry application is written in Java. It maintains a single communications channel with the Mac application, over which it receives requests to make, use and break network connections. The channel is multiplexed with ZooLib's Java ZStreamMUX on the BlackBerry side, and its C++ ZStreamMUX on the Mac.
Much of the Mac application's functionality is a C++ HTTP and port-forwarding proxy server, most of which is in ZHTTP. Its UI is implemented in Objective C using Cocoa Bindings.
The remainder of the Mac implementation effort was in reverse-engineering the BlackBerry/Host USB communications protocol.