Rated 3 out of 5 stars

to solar wind: browser.tabs.insertRelatedAfterCurrent is enabled (true) in my FF 3.6.16, but this works for links only. When other extensions opens tabs, they opened at the end of the tab queue.

There is an other version, compatible with FF 4.x : https://addons.mozilla.org/ru/firefox/addon/tabs-open-relative-modified/