REGISTER

Business Partner Network
The Business Partner Network is the single source for vendor data for the Federal Government. 
http://www.bpn.gov

Centralized Contractor Registration (CCR)
Federal Acquisition Regulation requires contractor registration in the CCR database prior to the award of any contract. 
http://www.ccr.gov

Dunn & Bradstreet (D&B)
Get listed and obtain a free D&B D-U-N-S Number for your company.
http://www.dnb.com

Small Business Source System (SBSS)
SBSS is an Internet-based database of information, open to all small
firms at no cost. Businesses profiled on the SBSS can be searched by
NAICS codes; key words; location; quality certifications; business type;
ownership race and gender; EDI capability and certification by SBA under
the 8(a)/HUBZone/Small Disadvantage Business Programs.
http://dsbs.sba.gov/dsbs/dsp_dsbs.cfm