I've been using Windows Live Writer for quite a while now and have been completely satisfied. I'm able to write when I'm traveling back and forth from San Diego but I wasn't really into bringing along my Powerbook until now. Of course, that posed one problem. Being only available for Windows, I had to find a Free Offline Blog Editor for Mac and stumbled onto Qumana. It's quite basic, and offers all the necessities for WYSIWYG editing. It's GUI is simple and its just as easy as using Windows Live Writer. The only draw back that I've found annoying is how slow the spell check runs, but so far, with writing 2 simply posts, I haven't had an issue. Check it out!!!
It also has an "Insert Ad" button which I'm going to play around with. Seems fun. There it is down below. It's cool, but I don't think that I'm going to really use it that much.
Powered by Qumana
edit: renamed qumana.com link to reflect the .htm to .php // thanks Mr. Christian Biggins