It’s simple, it’s a little bit manual, but it works well.
warmup.cmd assumes you have added the 12 hive to your path, else you can just fully qualify the path to stsadm. It’ll finish by calling your simple html page which will hit all the urls you want to warmup.
I use this iframe approach on my SharePoint admin site so I can see if all the site collections that I care about are up and running. Sometimes I throw a width=100% attribute in the iframe tag so all the websites stack on top of each other nicely.
This simple SharePoint warmup script is great to run at the end of your deployment scripts or as a task to put in your startup menu.
My other warmup script is a little bit of powershell which lists all of the site collection urls in the farm and adds them to the pages.html file, but I mostly just use the simple approach without powershell to start with at a new client site.