RESTful Patterns

What patterns exist for putting together RESTful services?

Detecting Lost Updates: Editing the Web - Detecting the Lost Update Problem Using Unreserved Checkout. A W3C Note from May of 1999!
Post Once Exactly: POST Once Exactly
Announced in a post from Mark Nottingham. Personally I think he missed a great opportunity to name it Post Only Once.

Any I'm missing? Let me know in the comments.

Query strings are a pattern for composing URIs. WebDAV collection hierarchy is a pattern for determining membership :).