National Women's Business Council: The NWBC is a bi-partisan federal advisory council that serves as an independent policy advisor to the President, Congress and the SBA on economic issues of importance to women business owners. You'll find research, news, and conference and event listings on the site.
Office of Women's Business Ownership: OWBO is a part of the SBA. Each SBA district office has a women's business ownership representative and there are women's business centers in nearly every state. OWBO also offers business training and technical assistance programs; provides access to credit and capital, federal contracts and international trade opportunities; and provides a nationwide network of mentoring roundtables. At OWBO's Online Women's Business Center, you can find lists of local reps and offices, as well as the business management information the SBA provides.
Women-21.gov: This site is a joint effort of the Department of Labor, the SBA and other partners. It brings together resources, articles, news, networking opportunities for women entrepreneurs.
WomenBiz.gov: This site is the "gateway for women-owned businesses selling to the government." It has useful links, event listings, and a step-by-step guide to government procurement.