This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I think a tool certification looks good. For example, if you wanted to market yourself to an IBM partner, look at getting a Rational Application Developer Certification. Development tool certs are fairly easy if you have the programming cert.
Or what about a server cert?
Where do you want to end up when your done? Let that lead you in the right direction.