On and off yesterday, when I'd spawn a new page from a link or refresh a forum page, the browser window would have back, forward, an empty space for refresh, stop and home buttons in the toolbar.
It hasn't done it today. I'm using Firefox 1.5.0.1. The only other time I have ever seen this was when you close down the forums for an apple event with one auto-refreshing page.
It just weirded me out because I'd be surfing like normal with the MacNN page behind several others, then come back to MacNN and go to hit refresh and nothing was there. I had to either open a new window or refresh using F5.