Firefox has a feature whereby you can press Ctrl with numbers from 1-8 to activate the corresponding tab in the browser. Put another way, Ctrl-1 activates the first tab (counting from the left) and Ctrl-8 activates the eighth tab from the left. I thought Ctrl-9 would do the ninth tab but it’s actually the right-most tab.
I’m a keyboard guy, but this feature never mattered to me much. I used Ctrl-Tab and Ctrl-Shift-Tab to cycle through my open browser tabs. Then I realized that there are a few pages, which some could describe as web-applications but that’s less important, that I almost always have open. I mean things like webmail or Pandora. I made a simple change of always having those tabs on the first few spots and now I can always get to them easily.