Since several people seemed interested in the older posts on inbox API usability I thought I'd point everyone to Steven Clark's blog on API usability. It looks like he's going through each of the cognitive dimensions and explaining them in detail. Very handy if you're interested in learning more about how to design usable APIs.
(By the way, in a strange circle of blogging links this post now completes the chain from his blog to ours. He linked to our API usability discussions last week!)
[Author: Neil Enns]