We always look to open source tools to optimize the value for our clients- we recommend PHPlist to send CAN SPAM compliant emails instead of something like Constant Contact, or using VTiger CRM instead of Salesforce. We use WordPress, Drupal or Joomla to build websites instead of proprietary CMS systems.
We’re a huge fan of Firefox- and all the great plugins, like FireFTP instead of using a commercial FTP program- and now, we find that there is a cross platform WYSIWG HTML editor for Mac, PC and Linux:
Kompozer has a lot going for it, foremost of which is the free-as-in-beer price tag. Kompozer sports tabbed editing—WYSIWYG in one tab, raw HTML in the other—on-the-fly editing via the built-in FTP site manager, and a highly customizable interface with easily modified toolbars. Kompozer has a markup cleaner and a W3C call function to validate your HTML against current standards. It’s free, available on Windows, Mac, and Linux machines, and it has a strong focus on standards compliance and clean code.
We’re big fans of Coda from Panic Software as a code editor- FTP app- but, it’s not really WYSIWG. We also love the firebug plugin to help track down properties of a misbehaving website- but, Kompozer is definitely worth a look.