Rated 4 out of 5 stars
Intuitive, like middle clicking on links.
But on one inner web-site (naumenSD) it works not perfect:
1) after middle-clicking submit button i have background tab with results (success)
2) in parent tab I can't middle-click submit button again or even left-click on submit button. Please try to find a fix if you can.
P.S.: Tests on http://dragtotab.mozdev.org/submittotab/ work fine as many times, as i click.