"Tekki Online" A.K.A "Metal Rage" it's a popular Third Person Shooter Game. Similar to Front Mission Online it focuses on team battles and mission modes where you battle out bosses too.
This game is out in Japan but has very high IP restrictions. I have yet to seen nor hear from someone who has been able to play outside of Japan.
But there are some rumors that it will be released Globally on January 2010 under the name of Metal Rage. Hope it arrives sooner and not too late, Since Front Mission already got ahead of it.