I've taken the Microsoft Office Specialist: Access 2003 exam. If you're a regular Access dev, then it will be pretty easy. I'd still go through a study guide, just to be safe. You'll be surprised at the new stuff you can learn!

As for VBA, the only VBA certification program I know of is the one VBAX has- it's specifically for Excel, but most of what you will learn will carry over to other Office programs. I took it and it was a good learning experience. It helped me learn some of the Excel object model.