I used SpyBot Search & Destroy to look at the things that were being started automatically. Nothing seemed amiss, but I disabled a bunch of stuff anyway. (It's a very handy little program and well worth a few bucks donation.)
I rebooted, and started Firefox with the 72 tabs I previously had open. After everything loaded and I saw no more action on the progress indicators on the tabs, I saw the 200 kB/s activity start up again.
So, I started closing tabs.
What do you know. The BP underwater cameras tab has movies that aren't being blocked by FlashBlock anymore. And what do you know, lots of things are happening with no indication on the tab that anything's happening.
http://www.bp.com/se...contentId=7063636
Yup. Closing that makes my network activity drop.
Sorry for the false alarm. Thanks for the help.
<goes away muttering to himself...>
Cheers,
Scott.