MarsEdit, http://www.red-sweater.com/marsedit/, looking quite good.
Firstly, easy to setup, I give it a label and http address, the MarsEdit goes and asks for my google userid and password, linked to my blog.
I then get a nice interface, with my categories, i.e., tags, a list of all of my blog entries, so simple.
So here I am, writing a blog entry. Lets see what it looks like on the other side.
...
On the other side, it doesn't look too bad.
And on the other side -
yip looks pretty good.