How to Design a Good API

I am interested in building an API for a small site. I found this nice document about building APIs (http://www.examville.com/examville/How%20to%20Design%20a%20Good%20API%20and%20Why%20It%20Matters%20-%20from%20a%20Google%20Engineer-ID6508). Can anyone refer similar documents that I can review about building APIs. Thanks!