Check out the International Institute of Business Analysts (IIBA). There you can find information on becoming CBAP (Certified Business Analysis Professional) certified. A PMP (Project Management Professional) certification is also well sought after. Many businesses value these types of professional organization credentials more so than corporate credentials, this is particularly true in the government sector where certifications must come from an independent source.
You may also want to look at corporate certification programs such as Microsoft's Certified Business Management Solutions Specialist & Professional. I'm sure other companies have similar "Business Analyst" like certifications.