One of my favorite toy lines of all time was
G.I. Joe Sigma 6. Based on the cartoon of the same name, it ran from 2005 to 2007 and featured Joes in not just one new scale, but
two: the 2.5" Mission figures, and the 8" Commandos.
Being a "joint junkie," I gravitated towards the bigger of the two, as they had more joints and more accessories. That combination beat out the presence of vehicles in the Mission playsets. The Commandos were big and chunky at 1:9 scale and featured weapons and equipment that you could mix and match between figures, giving you a ridiculous amount of play value.
The line managed to last about two years and around 80 figures, give or take, before finally throwing in the towel. If you'd like to look at the list of figures they released, there's a great site called
Joebattlelines.com that has detailed reviews of most of them (I think they're missing one or two exclusive re-colors like the Red Ninja), or check that old mainstay of Joe fans,
YoJoe.com (though their list seems less complete).
CoolToyReview.com also has an image gallery, though again, it's not as complete as the one at
Joebattlelines.com.
Of those 80 figures, I've got about 50, including this one called Sea Ops Duke.