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.
Snipt is a web service that attempts to solve a simple problem: storing commonly used snippets of code, and sharing them with your fellow coders. It seems to do that pretty well, with lots of good options for storing and sharing. Better yet, it has its Snipt API so coders can use this simple storage engine within their own programs.