Have a stamps module working.
Stamps.com method is a bit more convoluted.
Making progress on filtering out unwanted Stamps/USPS methods.
Now showing stamps/USPS shipping methods consistently.  Order grid uses Magento Shipping module to find available shipping methods.
Now able to fetch labels from stamps.com/USPS.  Hooray\!
Splitting up label generation logic into some helper classes.
Doing some configuration cleanup.