2 things at once

By having a popup window, I can follow 2 threads at once.

Is there a suitable way to do this with HTML?
or would anyone care to suggest a means using DHTML?

do popups have a use?

as an example of 2 threads visit the nearly complete shepherds pie 
recipe here: http://www.peepo.com/2k3/shepherds-pie/
one needs to make mince and mash at the same time, but interleaving 
these two processes would not be helpful.

Jonathan