How to Create a Good API

As a consultant that actually programms as well I interact with APIs on a regular basis. Some are good, some are bad, some are just hopeless. Most programmers know what they like about an API and what not, but actually creating a good API is a whole different story...

This video of the Google Techtalk "How to Design a Good API & Why it Matters" by Joshua Bloch is a great start. Joshua is a Principal Engineer at Google. He led the design and implementation of numerous Java platform features, including the Java Collections Framework.