Rated 4 out of 5 stars

I loved this is FF 3.*, so when I couldn't get it to work in FF 4.*, I tinkered around. This is how I got it to work:

If you've already installed URL Lister, remove it (Tools -> Add-ons -> Extensions -> Remove -> Restart Firefox)
right click on the window; New > Boolean
restart Firefox
install URL Lister again

The right click on a tab thing doesn't work for me, but URL Lister does appear in the "Tools" menu, which is good enough.