I am looking for a complete directory or database of IT (information
technology) or IS (information services) staffing/employment companies
in the US, such as Kforce or Allegis.  The actual directory or
database may be free or for-fee.

The listing must contain:
- a comprehensive listing of substantially all companies in this
space, small, large, private, or public
- no companies outside of the IS/IT staffing scope - no ASPs,
programming firms, executive search firms, etc.
- website and contact information
- detailed profiles of the companies are highly preferred (revenues,
employees, site locations)