This is not a question, just a comment that might be of interest to some viewers. I just discovered something I had never noticed before. With Firefox open and with too many tabs open to be displayed all at the same time on the tabs bar, hovering my wheel mouse over the tabs bar and then moving the wheel scrolls the tabs. Before now, I had always used the arrows at both ends of the tabs bar to scroll tabs.
I'm running Win 7 RC and Firefox 3.3.5 on the system with which I discovered this. I have not tried it with IE yet.