eBay4R is a Ruby wrapper for eBay's Web Services SOAP API. Has ease of use and small footprint. Instead of 40-50 line examples eBay gives you in C# and Java, with Ruby and eBay4R, examples are 5 lines or less.
FedTax's TaxCloud, the internet's only free sales tax service, now integrates with Stripe. Stripe will be TaxCloud's initial partner for TaxCloud.js, TaxCloud's new sales tax management API. Stripe merchants can now easily comply with any sales tax law in the US, regardless of state, with no extra charge to merchants.