In most cases I like to leave the double (mouse) fisting to the professionals, but ErgoClick is releasing a dual-mouse for the everyday user. The right mouse is used for movement and the left mouse is used for clicking. It is designed to be palm usage only to prevent repetitive stress injuries (RPI). Personally I'm a huge fan of the ergonomic keyboards, but I'm not sure I can take the plunge into this next generation of ergo madness.
Ergonomics comfort [DigiBuzz]