Roland V8 vision mixer
This is a powerful and versatile vision mixer. It has eight inputs. All can take a composite video input, four can take s-video, and there are two VGA inputs which can be switched onto an input too. There are pass-through outputs which can drive preview monitors without the need for distribution amplifiers.
This is a great choice for larger events with more complex visual requirements. We use it regularly for events needing multiple cameras for IMAG. However it can also be a more creative tool with lots of built in effects for VJing.