Aside from Dreamweaver, which has always been cross-platform, Apple's iWeb comes with the iWork suite and is even more intuitive and simple than CoffeeCup (which is PC only).
PodcastGenerator is cross-platform because it's actually a PHP script running on the webserver where your podcast is hosted.
There are many applications that can allow that, and one of the best (because it's cross-platform) is Qumana.
It's also limited to Blogger, but since it works through the web browser, it is a cross-platform editor.
This free application is cross-platform and includes tools for inserting ads into your posts.