This high-quality passive monitor controller can cater for five stereo input sources and three pairs of speakers, with built-in cue monitoring and talkback functions.
It's not exactly sexy, but this monitor matrix is certainly damn useful
Indigo I/O
Aureon 5.1 Fun
Sound Blaster Surround 5.1
UCA202 USB
Aureon 5.1 PCI
Traktor Audio 6