I think ATOM Publishing Protocol+OpenSearch (See GData) is shaping up as something special. There's a bit more to it than what I've provided below, but if you can speak HTTP then you will get the idea.
<Operation: HTTP Method, Path Info, Query String, Data>
Create: POST, /posts, nil, 'creating a post'
Read: GET, /posts/123, nil, nil
Update: PUT, /posts/123, nil, 'updated post'
Delete: DELETE, /posts/123, nil, nil
Search: GET, /posts, 'q=ruby', nil
technorati tags:atom, opensearch, gdata
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