The otherwise excellent Firefox plugin Slogger has a serious flaw in that logging a page that you got as the result of a POST request repeats the request. Thinking in RESTian terms, you're only supposed to consider results of GET requests static redoable and cacheable, not POST requests. If you're autologging something important you might get disappointing results after purchasing that book/deleting that DB records and so on and so on. This is a similar discussion as the one over Google Web Accelerator, but more serious, since this also involves POSTs and not just ill-considered GETs.

I'll update this post if someone posts a fix to the Slogger mailing list.