Microsoft recently published ReST API guidelines on GitHub. They are worth reading over if you design ReST APIs.
My Highlights:
- No limit on GET URL length
- Error response messages (consistency is the key; note the nesting of error info)
- Pagination: put the link for the next page into the response JSON. Interesting
- Delta queries: search, apply limiters
- Long running operations (start a job, come back later)