You can use AdBlock to block the iGoogle tab column. If you use AdBlock on Chrome, you can create the filter that you need, and then add it to AdBlock for Firefox. AdBlock on Chrome actually creates the filter, and you'll find the filter that it has made for you in the "Customize" tab of "Options". And you can bring that filter back to AdBlock on Firefox, and it works there.
This add-on used to work, but it looks like Google may be changing things too fast for the author to follow. Or maybe not, time will tell if this one gets back on track.