How do I create a loop-around world?

The multiple render way seems like the way to do it, but also a bit complicated though.

Heh, I was kinda hoping for a simpler solution, but the important thing now is knowing that I wouldn't be trying to do something the difficult way, when there was an easier way that I just didn't think about.

Thanks for the answers guys. It's given me a lot to think about and some different ideas to try out.

...still, if some of you comes up with a brilliant idea, I'd still like to hear it though. ;)