Came across this intriguing crowdfunded project for the Surface Pro today. The ProKASE is both a portfolio-style case and a mobile dock for your tablet.
According to the project's Indiegogo description, "The ProKASE protects the Microsoft Surface Pro and give it 3 USB3.0 ports, and a full sized SD/CF card reader. It can be used with or without the Mobile Dock."
I went ahead and made my contribution and should receive my ProKASE in late January. Look for a review next month.