multiple pcb interconnect
Hi,
I don't know about a 'large' system' but I regularly use ribbon cable, anything from 4-way to 50-way using headers (all of which are cheap). Ready built cables for computers are a cheap option.
Alternatively you can get 'edge' connectors, where a PCB plugs directly into the connector on another PCB, these are usually at right angles to each other. Check out 'molex' or 'harting' both are pretty major companies for interconnection solutions, and have a massive product line.
And, as always, tried google? something like 'PCB interconnect' seems to yeild a few 100000 results.
Buriedcode.