First mentioned it here but thought it deserves it's own post.
We used to be on Wordpress, so my wife got used to posting with MarsEdit. When I moved us to Statamic, she could no longer use MarsEdit.
That is, until I wrote an XML-RPC add-on that supports most of the Blogger/MetaWeblog/MoveableType API.
Please note I have only tested this with MarsEdit, so it may not work with other clients (but probably does).
If you have any problems, please let me know.