Markdown is this simple little language that can be auto-converted to HTML, but is much easier to write than HTML and uses a lot of email conventions. Italics are like *this* for example.
So there's a free Markdown editor for the Mac called "Mou." http://mouapp.com/
It shows your text on the left, how it is rendered on the right side, and it can auto-export in HTML when you're done. In addition, a lot of wikis support markdown. Here's a screen cap of Mou:
Anyway, it's terribly convenient if you have to create a lot of text for the web, it's free, and you don't have to mess around with the wackiness that is Dreamweaver.
There are a number of tools out there that will automatically convert Markdown to html, I just use Mou because it is so painless.
Oh, I just discovered that Textwrangler (also free) will convert Markdown. Neat.
Markdown in Textwrangler From Wikipedia:
Markdown is a lightweight markup language, originally created by John Gruber and Aaron Swartz allowing people "to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML)".[1] The language takes many cues from existing conventions for marking up plain text in email.
Markdown is also a Perl script written by Gruber, Markdown.pl, which converts marked-up text input to valid, well-formed XHTML or HTML and replaces left-pointing angle brackets ('<') and ampersands with their corresponding character entity references. It can be used as a standalone script, as a plugin for Blosxom or Movable Type, or as a text filter for BBEdit.[1]