There is only one file type that uses the .MASSEFFECTPROFILE extension:
Mass Effect Player Profile
File created by Mass Effect, a first person role-playing game where players complete missions in outer space; contains achievements for a player profile, including weapon skills (pistol, shotgun, assault rifle, etc.) and achievements; used to record player skills and progress.
MASSEFECTPROFILE files have the name Profile.MassEffectProfile and are located in the BioWare\Mass Effect\Save directory of a Mass Effect installation. They can be modified ("modded") using the Critical Mass editor.
Updated: January 11, 2010