ECWID Shipping labels
With the order API and a third party software, I've written a script to print shipping labels from ECWID. You have to launch the third party software, but it download and prints the labels for you. When ECWID's allows updating the tracking info, it will do that as well.
It seems to be working great for FedEx and USPS. You can print non postage bearing labels for USPS or labels with postage if you have a stamps.com account. I'm looking for a few people to help me test it out. Please let me know if you are interested.
I posted in the integration forum as well, but the post probably really belongs here.