Project Avenger

Project Avenger is an intiative of S.H.I.E.L.D. responsible for the assembly of the Ultimate Avengers.

Purpose
Although the exact purpose of the initiative has not been directly explained on-screen, it is implied that it employs people with special powers to defend the United States and humanity against threats.

Involvement
Those involved with the Avenger Initiative include:

Nick Fury
Fury is the director of S.H.I.E.L.D. who takes personal interest in Project Avenger

Steve Rogers
Fury promoted Rogers to lead the team.