Hmm...I read it like you want help figuring out the topic of the dry erase board, not the decorations. Am I right? Here's what comes to mind.
-Something schedule related, like time of last feeding and diapering.
-A baby meal planning board that you'd use when you started solids. You could keep track of which solids you've tried, which you plan to feed her at each meal for the week, and what you're running low on. For that, maybe this kit:
-An info board for babysitters with spaces for where you'll be, your contact info, her schedule (esp. meals and sleep), the peds phone number, poison control, and notes.