I'd look first at IBM's Certification Programs and see if one is offered that's relevant to you and your expertise. Otherwise, you could try a company like Brainbench and see what they offer for you. And, there are professional certifications (Project Management, ITIL, Security) and vendor-specific certifications (Cisco, SAP, SAS, EMC, etc.).
There is a comment on the Wikipedia site concerning professional and IT certifications:
The current proliferation of IT certifications has led some technologists to question their value. Proprietary content that has been distributed on the Internet allows some to gain credentials without the implied depth or breadth of expertise. Certifying agencies have responded in various ways: Some now incorporate hands-on elements, anti-cheating methodologies or have expanded their content. Others have expired and restructured their certificate programs, and/or raised their fees to deter abuse.
Certification programs that take into account length of service, and demonstrated experience, via industry peer and/or employer recommendation avoid some of the issues associated with purely passing an examinations; however, certification remains a contentious issue.
Also, some professional certifications require a criminal record check for the certification to be approved. The presence of a criminal history when applying for certification may be grounds for denial of certification.