Read-it-later service Instapaper has released what it's calling a "full API." With it, developers using the Instapaper API can create applications that both write to and read from the service. The full API is free to developers, but only paying users can read from their Instapaper account using third-party tools.
GoPollGo is all about creating polls, from running them during presidential debates to coworkers polling each other on where to go for lunch. It has two APIs. One is a public read-only API free to anyone. The other is private, in beta that allows third parties to create polls. Clients such as ESPN, Netflix, Hotels.com, Robert Scoble, AppleInsider and The Weather Channel, use GoPollGo to track opinions on their brands and businesses.