What's a good web development application?

I think that depends on what you want to do.

If you want to build themes for Drupal, WordPress or Joomla... or even just general html pages... Artisteer might be what you're looking for.

http://artisteer.com

For coding, I use Xcode. I've created plenty of UIWebView apps with it, which are basically self-contained websites. Also, gedit is another way to manually edit code...

http://projects.gnome.org/gedit/

I use that for PHP / JavaScript / HTML because it makes the code look pretty. It colorizes the code for easy readability. I recently switched from a Windows PC. I think Notepad++ is better, but gedit is close enough.

I actually hate Dreamweaver. It's so bloated. I don't know how it became something of a standard. Heh, although, I'm someone who actually liked FrontPage, so my perspective might be quite different than the average web developer.

There are open source editors too. Like Seamonkey - that's a collection of web apps, and an editor is included.

http://www.seamonkey-project.org/

I don't use that though. Heh... and I don't use this...

http://kompozer.net/

...but it is another possibility. Aside from Artisteer, I think the Mac is actually lacking a really good WYSIWYG HTML editor. Maybe things will change with the Mac App Store.